CA1103256A - Proline derivatives and related compounds - Google Patents
Proline derivatives and related compoundsInfo
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- CA1103256A CA1103256A CA349,475A CA349475A CA1103256A CA 1103256 A CA1103256 A CA 1103256A CA 349475 A CA349475 A CA 349475A CA 1103256 A CA1103256 A CA 1103256A
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- proline
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- lower alkyl
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Abstract
Abstract of the Disclosure New proline derivatives and related compounds which have the general formula
Description
11~135b S~
This invention relates to new proline derivatives and related compounds which have the general formula (I) IR4 ~ 2C - (CH) R2- S - (C*~i)n~ CO - N ~ COR
wherein R is hydro:;y, N~12 or lower alkoxy;
Rl and R4 each is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl;
R2 is hydrogen, lower alkyl, phenyl, substituted phenyl wherein the phenyl substituent is halo, lower alkyl or lower alkoxy, phenyl-lower alkyl, diphenyl-lower alkyl, triphenyl-lower alkyl, lower alkylthiomethyl, phenyl-lower alkylthiom thyl, lo~Mer alkanoMyl-amidom~thyl, R5-C-, R5-M-C-,R5-N~I-C-,R6-S- or ~7;
R3 :i, hyclroyen,hyclroxy or lower alkyl;
R5 is lower alkyl, phenyl or phenyl-lower --1-- :
~ .' . :'"~
IA135b alk~l;
R6 is lower alkyl, phenyl, substituted phenyl, ~wherein the phenyl substituent is halo, lower alkyl or lower alkoxy), hydroxy-lower alkyl or amino(carboxy)-lower alkyl;
m( * 1 2 Rl R4 R is R-OC-IIC - N - CO _ CH-- (CH)-- S(O) ;
7 * * * n p M is 0 or S;
m is 1 to 3;
n and p each is 0 to 2, and to processes for making them.
The asterisks indicate asymmetric carbon atoms.
Each of -the carbons bearing a substituent Rl, R3 and R4 is asymmetric when that subs-tituent is other than hydroyen.
The invention in its broad aspects includes proline and related derivatives having formula I above. Within this broad group, because of their properties, certain subgroups are preferred over others.
Broadly preferred are those compounds of formula I
wherein R is hydroxy or lower alkoxy; Rl is hydrogen or lower alkyl; R2 is hydrogen, R5-CO, R6-S-, or R7; R3 and R4 each is hydrogen; R5 is lower alkyl, especially methyl or phenyl; R6 is lower alkyl, especially methyl or ethyl;
m is 2, n is 0~ 1 or 2, especi~lly 1; and R7 wherein ~, Rl, R3, R~l, m and n have thc s~le preferences as abovc ancl p is 0.
s~;
Especlally preferred are those compounds whicll have the f ormu 1 a (II) R2 S - (CH ) CH--CO- N COR
* *
wherein R is hydroxy or lower alkoxy;
Rl is hydrogen or lower alkyl;
R2 is hydrogen, R5-cO-~ R6-S- or R7;
R5 is lower alkyl or phenyl, especially the first;
R6 is lower alkyl;
and n is 0, 1 or 2.
Within the group of compounds represented by formula II, the following are still more ~referred subgrouFs in the order (a to r~ of increasing preference to the com-pounds which are especially preferred embodiments:
a) R is hydroxy b) n is 1 c) R2 is hydrogen or lower alkanoyl d) R2 is hydrogen e) R2 is acetyl f) Rl is hydrogen or lower alkyl g) Rl is hydrogen or methyl h) R is hydroxy, Rl is hydrogen or methyl i) R is hydroxy, Rl is hydrogen or methyl, R2 is hydro-gen or acetyl and n is 0, 1 or 2 }3 ~ i~ hy~r~xy, ~ ~n~ n2 ~ach is hydro~n an~ n is ~ :
,. ~
. k) R is hydroxy, Rl is hydrogen, R2 is acetyl and n is 1) R is hydroxy, Rl is methyl, R2 is acetyl and n is 1 m) R is hydroxy, Rl and R2 each is hydrogen and n is 1 n) R is hydroxy, Rl is methyl, R2 is hydrogen and n is o) R is hydroxy, Rl is hydrogen, R2 is lower alkylthio and n is 1 p) R2 is lo ~ 71 R-OC N - OC- CH - (CH2)n-S-;
each R is hydroxy; Rl is hydrogen or lower alkyl, es-pecially hydrogen or methyl; and n is 0 to 2, es-pecially 1 q) R2 is R5-M-C- wherein M is O or S
M
r) R2 is R5-NH-C- wherein M is O or S, preferably S.
It will be appreciated that combinations of the fore-going, where applicable, are among the preferred groups.
The stereoisomers in which the proline is in the L-form are especially preferred.
The lower alkyl groups represented by any of the vari-ables include straight and branched chain hydrocarbon radicals from methyl to heptyl, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, iso-pentyl and the like. The lower alkoxy groups are of the same kind having 1 to 7 carbons linked to oxygen, for ex- ~
ample, methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, t-butoxy and the like. The Cl-C4 members, espe-cially Cl and C2 members, of both .
11.~135~) types are preferred. Phellylmethyl is the preferred phenyl-lower alkyl gro-lp.
The lower alkanoyl groups are -those havirlg the acyl radicals of the lower (C2-C7) fatty acids, for example, acetyl, propionyl, bu~yryl, isobutyryl and the like. Similarly, those lower alkanoyl groups having up to four carbons, and especially acetyl, are preferred.
The four common halogens are included by the term "halo" but chlorine and bromine are preferred. The substi-tuted phenyl groups preferably bear the substituent in the 4-position of the ring. The hydroxy-lower alkyl groups have a hydroxy group on an alkyl chain like those described above, preferably on the terminal carbon, e.y., hydroxymethyl,
This invention relates to new proline derivatives and related compounds which have the general formula (I) IR4 ~ 2C - (CH) R2- S - (C*~i)n~ CO - N ~ COR
wherein R is hydro:;y, N~12 or lower alkoxy;
Rl and R4 each is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl;
R2 is hydrogen, lower alkyl, phenyl, substituted phenyl wherein the phenyl substituent is halo, lower alkyl or lower alkoxy, phenyl-lower alkyl, diphenyl-lower alkyl, triphenyl-lower alkyl, lower alkylthiomethyl, phenyl-lower alkylthiom thyl, lo~Mer alkanoMyl-amidom~thyl, R5-C-, R5-M-C-,R5-N~I-C-,R6-S- or ~7;
R3 :i, hyclroyen,hyclroxy or lower alkyl;
R5 is lower alkyl, phenyl or phenyl-lower --1-- :
~ .' . :'"~
IA135b alk~l;
R6 is lower alkyl, phenyl, substituted phenyl, ~wherein the phenyl substituent is halo, lower alkyl or lower alkoxy), hydroxy-lower alkyl or amino(carboxy)-lower alkyl;
m( * 1 2 Rl R4 R is R-OC-IIC - N - CO _ CH-- (CH)-- S(O) ;
7 * * * n p M is 0 or S;
m is 1 to 3;
n and p each is 0 to 2, and to processes for making them.
The asterisks indicate asymmetric carbon atoms.
Each of -the carbons bearing a substituent Rl, R3 and R4 is asymmetric when that subs-tituent is other than hydroyen.
The invention in its broad aspects includes proline and related derivatives having formula I above. Within this broad group, because of their properties, certain subgroups are preferred over others.
Broadly preferred are those compounds of formula I
wherein R is hydroxy or lower alkoxy; Rl is hydrogen or lower alkyl; R2 is hydrogen, R5-CO, R6-S-, or R7; R3 and R4 each is hydrogen; R5 is lower alkyl, especially methyl or phenyl; R6 is lower alkyl, especially methyl or ethyl;
m is 2, n is 0~ 1 or 2, especi~lly 1; and R7 wherein ~, Rl, R3, R~l, m and n have thc s~le preferences as abovc ancl p is 0.
s~;
Especlally preferred are those compounds whicll have the f ormu 1 a (II) R2 S - (CH ) CH--CO- N COR
* *
wherein R is hydroxy or lower alkoxy;
Rl is hydrogen or lower alkyl;
R2 is hydrogen, R5-cO-~ R6-S- or R7;
R5 is lower alkyl or phenyl, especially the first;
R6 is lower alkyl;
and n is 0, 1 or 2.
Within the group of compounds represented by formula II, the following are still more ~referred subgrouFs in the order (a to r~ of increasing preference to the com-pounds which are especially preferred embodiments:
a) R is hydroxy b) n is 1 c) R2 is hydrogen or lower alkanoyl d) R2 is hydrogen e) R2 is acetyl f) Rl is hydrogen or lower alkyl g) Rl is hydrogen or methyl h) R is hydroxy, Rl is hydrogen or methyl i) R is hydroxy, Rl is hydrogen or methyl, R2 is hydro-gen or acetyl and n is 0, 1 or 2 }3 ~ i~ hy~r~xy, ~ ~n~ n2 ~ach is hydro~n an~ n is ~ :
,. ~
. k) R is hydroxy, Rl is hydrogen, R2 is acetyl and n is 1) R is hydroxy, Rl is methyl, R2 is acetyl and n is 1 m) R is hydroxy, Rl and R2 each is hydrogen and n is 1 n) R is hydroxy, Rl is methyl, R2 is hydrogen and n is o) R is hydroxy, Rl is hydrogen, R2 is lower alkylthio and n is 1 p) R2 is lo ~ 71 R-OC N - OC- CH - (CH2)n-S-;
each R is hydroxy; Rl is hydrogen or lower alkyl, es-pecially hydrogen or methyl; and n is 0 to 2, es-pecially 1 q) R2 is R5-M-C- wherein M is O or S
M
r) R2 is R5-NH-C- wherein M is O or S, preferably S.
It will be appreciated that combinations of the fore-going, where applicable, are among the preferred groups.
The stereoisomers in which the proline is in the L-form are especially preferred.
The lower alkyl groups represented by any of the vari-ables include straight and branched chain hydrocarbon radicals from methyl to heptyl, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, iso-pentyl and the like. The lower alkoxy groups are of the same kind having 1 to 7 carbons linked to oxygen, for ex- ~
ample, methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, t-butoxy and the like. The Cl-C4 members, espe-cially Cl and C2 members, of both .
11.~135~) types are preferred. Phellylmethyl is the preferred phenyl-lower alkyl gro-lp.
The lower alkanoyl groups are -those havirlg the acyl radicals of the lower (C2-C7) fatty acids, for example, acetyl, propionyl, bu~yryl, isobutyryl and the like. Similarly, those lower alkanoyl groups having up to four carbons, and especially acetyl, are preferred.
The four common halogens are included by the term "halo" but chlorine and bromine are preferred. The substi-tuted phenyl groups preferably bear the substituent in the 4-position of the ring. The hydroxy-lower alkyl groups have a hydroxy group on an alkyl chain like those described above, preferably on the terminal carbon, e.y., hydroxymethyl,
2-hydroxyethyl, etc. The amino(carboxy)lower alkyl groups have one amino and one carboxy on a lower alkyl group such as those described above, preferably both on one carbon, e.g., on the terminal carbon as in the preEerred 2-amino-2-carboxyethyl group.
The products of formula I and the preferred subgroups can be produced by various methods of synthesis.
In general, the products-of this invention are produced by acylating a compound of the formula ~III) H2C-- (Cll)m ~ N Cll - COR
with an acid of the formula (IV) R~ R
2 ( )n _ ,j_ ~ 3Al35b or its chemical equivalent.
Thus, the final product can be produced not only by direct acylation ~ith an acid of forrnula IV but also by intermediates such as ~a) ~-haloalkanoic acids of the formula R4 Rl (V) l I
X - (CH)n-- - CH - COOH
wherein X is bromo, chloro or iodo, or (b) a tosyloxyalkanoic acid, i.e., X in formula V is tosyloxy (CH3 ~ SO2O-) (c) a substituted acrylic acid of the formula 14 1l (VI) CH - C COOH
The product of this acylation is then subjected to displacement or addition with the anion of a thiol or thioacid of the formula (VII) R2 SH
Acylation can also be effected with a thiolactone of the formula IR4 IRl l (VIII) (fH) -- fH
S =O
wherein n is l or 2, or a mercaptoalkanoic acid of the formula (IX) ~ )n COR
I-IA135b wherein Y is ~ or, in aclclition, i~ a produc~ of formula I
wherein R2 is hydrogen is desired, then Y can also be a protecting group such as (a)RlC~l3O~ CH2 , ( ) ~
(c) CH3CONHCH2, (d) I~-O-C-C~I-(C~-I) -S- or other sulfur protectinc3 group. "Deprote~ction" can be effected by eonventional means sueh as treatment with hot trifluoroacetic aeid, cold trifluoromethanesulfon:ic aeid, mercuric acetate, sodium in liquid ammonia, zinc and hydrochloric acid or the like. For a review of these methods see Methoden der Organisehen Chemie (Houben-Weyl), Vol. XV, part I, page 736 et seq. (1974).
When the acid of formula IV is used as the aeylating agent, the aeylation can be effeeted in the presence of a eoupling agent like dicyelohexyearbodiimide or the like, or the aeid ean be aetivated by formation of its mixed annydride, symmetrieal anhydride, aeid chloride, acid ester or use of Woodward reagent K, N-ethoxyearbonyl-2-ethoxy-1,2-dihydroquinoline or the like. For a review of the methods for aeylation, see Methoden der Organischen Chemie (Houben-Weyl), Vol. XV, part II, page 1 et seq. (1974).
Compounds of formula III include, for example, proline, hydroxyproline, 4-methylproline, pipeeolic acid, 5-hydroxypipecolie aeid, azetidine-2-carboxylic acid, their lower alkyl esters and the like. The aeylation of sueh compounds is described in greater detail below.
According to a preferred method for producinc3 compounds oî formula I, espeeially wherein R2 is r~5-CO-, an acid or ester of formula III is coupled with a haloalkanoic acid of the formula ~:f~
HAl35b (V) R R
14 1l ;
( )n ~herein X is a haloc3ell, prcferably chlorine or bromine. This can be effectecl by one of the known procedures in which the acid IV is activated, prior to reaction ~ith the acid III, involving formation of a mixed anhydride, symmetrical anhydride, acid chloride, active estcr, or use of Woodward reayent K, EEDQ
(N-ethoxycarbonyl-2-ethoxy-l,2-dihydroxyquinoline) or the like.
The product of this reaction is a compound of the formula (X) IR3 - 14 1l H2C - (CH) X - (C11) - C~1- CO - N C~1-COR
The product of formula X is subjected to a displaccmcnt reaction with the anion of a thioacid of the formula (VII) R2-S~I
yielding a product of the formula (XI) IR3 ,`
14 ~ 2C- (C~l)m R2- S - (C1~ C~l-CO - N - CII-COR
When R2 is R5CO, this product can thcn bc converted to the product (XII) R3 R4 ~ 2C (C11)m i-lS - (C11) - CH - CO - N CH-COR
by ammonolysis. When R2 is a protecting group, -then the compound of formula XII can be ob-tained by "depro-tec-tion"
as described above. When R is an ester group (i.e., R is lower alkoxy), the ester group can be removed, e.g., when R is tert. butoxy or tert. amyloxy, by trea-tment of the ester of formula XI or XII wi-th trifluoroacetic acid and anisole to give the corresponding free acid. When o-ther alkoxy groups are present, alkaline hydrolysis will yield the corresponding acid.
A variation of this procedure involves the use of an acrylic acid of 'he formula ~VI) R4 Rl CH=C-COOH
as starting material. This acrylic acid is first conver-ted to the acid halide form then made to react with a compound of formula III to obtain a compound of the for-mula R3 (XIII) IR4 IRl H2CI (CH)m CH=C - CO - N CH-COR
and this intermediate is subjected to the addition reac-tion with the thiol or thioacid VII as described above.
A tosyloxyalkanoic acid of the formula (XIV) IR4 IRl CH3- ~ _ S020-(CH)n CH - COOH
can also be used as the agent to acylate the acid of formula III, then the acylation product is subjected to the displacement reaction, etc., as described above.
The acrylic acid of formula VI can alternatively be firs-t made to react with the thioacid of formula VII to ' obtain a product of the formula (XV) R14 IRl which is converted to i-ts acid halide, e.g., with thionyl chloride, then coupled to the compound of formula III and the same sequence as above then followed.
The acid or ester of formula III can also be acylated with a "protected" form of a ~-mercaptoalkanoic acid of the formula (XVI) 4 R8-s-(cH)n-cH-cooH
wherein R8 is the "protecting" group. Such "protecting"
groups can take the form described above.
Following the acylation, the product can be "depro-tected" by one of the known methods referred to above.
Still another acylating agent can take the form of a thiolactone, e.g., ~-propiothiolactone, N-methyl-~-pro-piothiolactone or the like.
Additional details of preferred modes of producing compounds of this invention can be found in the following and in the specific examples.
According to a particularly preferred modification, the acid or ester of formula III is acylated with a halo-alkanoyl halide of the formula (XVII) 14 1l X-(CH)n CH-COX
wherein each X is independently a halogen, preferably chlorine or bromine, Rl is hydrogen, lower alkyl or phenyl-lower alkyl .~ . . . .
J' ~S~
and n is 0, 1 or 2. This r~action is effected in an alka-line medium, e.g., dilute alkali metal hydroxide solution, alkali metal dicarbonate or alkali metal carbona-te solution at a reduced temperature, e.g., about 0 to 15C. The re-action product is subjected to displacement with the anion of the thiol or thio acid of the formula VII above, also in alkaline medium, preferably alkali metal carbonate so-lution, and then worked up in conventional manner. The product of this reaction, wherein R2 of formula I is R5-CO, is converted to the product wherein R2 is hydrogen by ammonolysis, e.g., alcoholic ammonia or concentrated ammonium hydroxide solution, or alkaline hydrolysis, e.g., with aqueous metal hydroxide. When an acid of formula III is used as starting material, the final product ob-tained as the free carboxylic acid can then be converted to its ester, for example by esterification with a dia-zoalkane, like diazomethane, l-alkyl-3-p-tolyl-triazene, like l-n-butyl-3-p-tolyltriazene or the like. Treatment of an ester, preEerably the methyl ester, with an alco-holic ammonia solution, converts the free acid to theamide, i.e., R is NH2.
According to another variation, an ester, prefer-ably the t-butyl ester, of formula III, in an anhydrous medium such as dichloromethane, tetrahydrofuran, dioxane or the like, is treated with a thioalkanoic acid of the formula (XVIII) IRl R2-S-(CH2)n ---- CH - COOH
in the presence oE dicyclohexylcarbodiimide, N,N'-car-bonyl-bisimidazole, ethoxyacetylene, diphenylphosphoryl azide or similar coupling agents at a temperature in the range of about 0 to 10C. The ester group (R) can then be removed, for ;2 5~
example, by treatment with trifluoroacetic acid and ani-sole at about room temperature.
When an ester of formula III (e.g., R is lower al-koxy, especially, t-butoxy) is acylated with a thiolactone, e.g., ~-propiothiolactone, ~-methyl-~-propiothiolactone or the like, the reaction can be effected in an anhydrous solvent like tetrahydrofuran, dioxane, methylene chloride or the like at about 0 C. to about room temperature. The ester group can be removed with anisole and trifluorace-tic acid as described above. M
In similar manner, when R2 is R5-M-C-, products of formula I having this substituent are formed by reacting a compound of formula XII with the halogenated compound ~XIX) M
or alternatively reacting a compound of formula X with an alkali metal salt or alkaline earth metal salt of the formula tXX) M
R5-M-C-S-Me wherein Me represents the alkali metal or alkaline earth metal. M
.
~ hen R2 is R5-NH-C-, products of formula I having this substituent are produced by reacting a compound of formula XII with the appropriately substituted isocyanate or isothiocyanate of the formula (XXI) R5-N=C=M
Alternatively, the same products can be produced by coup-ling an acid of the formula ~- -12-,.~
IIA 1 3 5 b ( .`;X I I ) M R R
R5-NEI-C-S- (CE~)-- CH-COOEI
with an amino acid of formllla IlI.
Compounds of formula I, wilerein R2 is lower alkyl, phenyl, substituted phenyl, phenyl-lower alkyl, -triphenyl-lower alkyl, lower alkylthiomethyl or phenyl-lower alkylthiomethyl are produced by reacting a compound of formula XII with the corresponding halide R~X or ~y reacting a compound of formula X
with the corresponding thiol R2SH in the same manner as described above.
When R2 is lower alkanoylamidomethyl, the product of formula I is produced by condensing a compound of formula XII
with the corresponding hydroxymethyl-lower alkanoylamide of the formula ~XXIII) lower alkyl-CO-NHCH2OH
in the presence of an acid catalyst like trifluoroacetic acid.
Products of formula I wherein R2 is R6-S can be prepared by any of the known methods for the synthesis of mixed disulfides, e.g., by the reaction of a compound of formula(XII)with a thiosulfinate(xxIv), thiosulfonate (XXV), sulfenyl halide (XXVI), thiosulfate (XXVII) or sulfenyl thiocyanate (XXVIII) O
(XXIV) R6-S-S-R6, (XXV) R6-S-S-R6, (XXVI) R6S-X, O
(XXVII) R6-S-S03H, (XXVIII) R6-S-SCN
In the particular case wherein R7 is R R CEE -- (CH) 14 1l 1 2 1 n -S (O) ---- (CE~ CH-- CO-- N -- CH-COR, s~
~IA135b R, R , R3 and R4 are the same as the corresponding substituents in formula I and p is O, the symmetrical disulfides can be obtained by direct o~cidation of a compound of formula XII
with iodine. ~hen p is 1 or 2, such products are obtained by the stepwise oxidation of the corresponding compound wherein p is O. Mixed disulfides are obtained by the modification shown in the examples.
Products of formula I have one or more asym~etric carbons.
When Rl, R3 or R4 is other than hydrogen the carbon to which it is attached is asymmetric. These carbon atoms are indicated by an asterisk in formula I. The compounds accordingly exist in stereoisomeric forms or in racemic mixtures thereof. All of these are within the scope of the invention. The above described synthesis can utilize the racemate or one of the enantiomers as starting material.
~hen the racemic starting material is used in the synthetic procedure, the stereoisomers obtained in the product can be separated by conventional chromatographic or fractional crystallization methods. In general, the L-isomer with respect to the carbon of the amino acid constitutes the preferred isomeric form. Also the D-isomer with respect to the a-carbon in the acyl side chain (i.e., the carbon bearing Rl) is preferred.
The com~ounds of this invention form basic salts with various inorganic and organis bases which are also within the scope of the invention. Such salts include ammonium salts, alkali metal salts like sodium and potassium salts (which are preferred), alkaline earth metal salts like the calcium and magnesium salts, salts with organic bases, e.g., dicyclohexylamine salt, benzathine, N-methyl-D-glucamine, --1~--.. ..
~-IA135b hydrabamine salts, salts with amino acids like arginine, lysine and the like. The non-toxic, physiologically acceptable salts are preferred, although other salts are also useful, e.g., in isolating or purifyincJ the procluct, as illustrated in the examples in the case of tne dicyclohexylamine salt.
The salts are formed in conventional manner by reacting the free acid form of the product with one or more equivalents of the appropriate base providing the desired cation in a solvent or medium in which the salt is insoluble, or in ~ater and removing the water by freeze drying. By neutralizing the salt with an insoluble acid like a cation exchange resin in the hydrogen form (e.g., polystyrene sulfonic acid resin like Dowex 50) or with an aqueous acid and extraction with an organic solvent, e~g., ethyl aceta-te, dichloromethane or the like, the free acid form can be obtained, and, if desired, another salt formed.
~ dditional experimental details are found in the examples which are preferred embodiments and also serve as models for -the preparation of other members of the group.
The compounds of this invention inhibit the conver-sion of the decapeptide angiotensin I to angiotensin II
and therefore are useful in reducing or relieving angio-tensin related hypertension. The action of the enzyme re-nin on angiotensinoqen, a pseudoglobulin in blood plasma, produces angiotensin I. Angiotensin I is converted by angiotensin converting enzyme (ACE) to angiotensin II.
The latter is an active pressor substance which has been implicated as the causative agent in various forms of hypertension in various mammalian species, e.g., rats and dogs. The compounds of this invention intervene in the angiotensin(renin)~angiotensin I ~angiotensin II sequence by inhibiting angiotensin converting enzyme and reducing or eliminating the formation of the pressor substance angiotensin II. Thus by the administration of a composi-tion containing one or a combination of compounds of for-mula I or physiologically acceptable salt thereof, angio-tensin dependent hypertension in the species of mammal suffering therefrom is alleviated. A single dose, or pre-ferably two to four divided daily doses, provided on a basis of about 0.1 to 100 mg. per kilogram per day, pre-ferably about 1 to 50 mg. per kilogram per day is appro-priate to reduced blood pressure as indicated in the ani-mal model experiments described by S.L. Engel, T.R.
Schaeffer, M.H. Waugh and B. Rubin, Proc. Soc. Exp. Biol.
Med. 143, 483 (1973). The substance is preferably admin-istered orally, but parenteral routes such as subcutaneous,intramuscular, intravenous or ~i .
5~
intraperitoneal can also be employed.
The compounds of this invention can be utilized to achieve the reduction of blood pressure by forn~lating in compositions such as tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral aclministration. About 10 to 500 mg. of a compound or mixture of compo~mds of formula I or physio-logieally acceptable salt is compounded with a physiologically aecep-table vehiele, carrier, excipient, binder, preservative, stabilizer, flavor, ete., in a unit dosage form as called for by accepted phar-maceutieal practice. The amount of active substance in these com-positions or preparations is such that a suitable dosage in the range indieated is obtained.
Illustrative of the adjuvants which may be incorporated in tablets, capsules and the like are the follcwing: a binder such as gum tragacanth, aeaeia, eorn stareh or gelatin; an exeipient such as diealeium phosphate; a disintegrating agent such as corn stareh, potato stareh, alginie aeid and the like; a lubrieant sueh as magnesium stearate; a s~eetening agent sueh as suerose, laetose or saeeharin; a flavoring agent such as peppermint, oil of winter-green or eherry. When the dosage unit form is a eapsule, it mayeontain in addition to materials of the above type a liquid earrier such as a fatty oil. Various other materials may be present as eoatings or to otherwise modify the physieal form of the dosage unit. For instanee, tablets may be eoated with shellae, sugar or both. A syrup or elixir may eontain the aetive compound, suerose as a sheetening agent, methyl and propyl parabens as preservatives, a dye and a flavorinq sueh as cherry or orange flavor.
Sterile eom~sitions for injeetion ean be formulated .
~3~5~
according -to conventional ~harmaceutical praetiee by dis-solving or suspending the active substance in a vehicle such as water for injection, a naturally occurring vege-table oil like sesame oil, coconut oil, peanut oil, cotton-seed oil, ete., or a synthetic fatty vehicle like ethyl oleate or the like. Buffers, preservatives, antioxidants and the like ean be ineorporated as required.
The following examples are illustrative of the in-vention and eonstitute espeeially preferred embodiments.
All temperatures are in degrees celsius.
. .,. ,~ _ -E:;ample 1 senzoylthioacetyl)-L-Proline L-Proline (5.75 q.) is dissolved in N sodium hydr-oxide (50 ml.) and the solution is chilled in an ice-water bath. Sodium hydroxide 2N (26 ml.) and chloroacetyl chlo-ride (5.65 g.) are added and the mixture is stirred vigo-rously at room temperature for three hours. A suspension of thiobenzoic acid (7.5 g.) and potassium carbonate (4.8 g.) in water (50 ml.) is added. After 18 hours stirring a~ room temperature, the reaction mixture is acidified and extracted with ethyl acetate. The ethyl acetate layer is washed with water, dried over magnesium sulfate and con-centrated to dryness in vacuo. The residue (14.6 g.) is dissolved in ethyl acetate (150 ml.) and dicyclohexylamine ~ -(11 ml.) is added. The crystals are filtered and recry-stallized from ethyl acetate, yield 5.7 g. m.p. 151-152.
To convert the salt to the acid, the crystals are dissol-vea in a mixture of 5~ aqueous potassium bisulfate (100 ml.) and ethyl acetate (300 ml.). The organic phase is washed once with water, dried over magnesium sulfate and concentrated to dryness in vacuo, yield 3.45 g.
Example 2 1-(2-Mercaptoacetyl)-~-Proline 1-(2-Benzoylthioacetyl)-L-proline (3.4 g.) is dis-solved in a mixture of water (10.5 ml.) and concentrated ammonia (6.4 ml.). After one hour, the reaction mixture is diluted with water and filtered. The ~iltrate is ex-tracted with ethyrl acetate and then acidified with con-centrated hydrochloric acid, saturated with sodium chlo-ride and extracted twice with ethyl acetate. The ethylacetate extracts are washed with saturated sodium chlo-ride and concentrated to dryness, yield 1.5 g.
Tne product, 1-(2-mercaptoacetyl)-L-proline is crystallized from ethyl acetate (m.p. 133-135).
Example 3 1-(2-Benzoylthioacetyl)-L-Proline Methyl Ester 1-(2-Benzoylthioacetyl)-L-proline obtained in Example 1, is dissolved in methanol and an ethereal solution of diazomethane is added until there is a persistent yellow color. ~fter 15 minutes, a few drops of acetic acid are added and the solvent is removed in vacuo to obtain l-t2-benzoylthioacetyl)-L-proline methyl ester.
Example 4 1-(2-Mercaptoacetyl)-L-Proline Amide The product of Example 3 is dissolved in 10~ metha-nolic ammonia and the solution is stored at room tempera-ture in a pressure bottle. When thin layer chromatogra-phic analysis indicates that the two ester functions have been ammonolyzed, the reaction mixture is concentrated to dryness to obtain l-(2-mercaptoacetyl)-L-proline amide.
Example 5 1-~2-Benzoylthioacetyl)-L-Hydroxyproline By substituting L-hydroxyproline for the L-proline in the procedure of Example 1, 1-(2-benzoylthioacetyl)-L-hydroxyproline is obtained.
Example 6 1-(2-Mercaptoacetyl)-L-Hydroxyproline By treating the product of Example 5 with ammonia as in Example 2, 1-(2-mercaptoacetyl)-L-hydroxyproline is obtained.
Example 7 1-(2-Benzoylthioacetyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid for the `~
- ~ .
.3~
L-proline in the procedure of Example 1, 1-(2-benzoylthio-acetyl)-L-azetidine-2-carboxylic acid is ob-tained.
Example 8 1-(2-Mercaptoacetyl)-L-Azetidine-2-Carboxylic Acid By treating the product of ~xample 7 with ammonia as in Example 2, 1-(2-mercaptoacetyl)-L-azetidine-2-car-boxylic acid is obtained.
Example 9 1-(2-Benzoylthioacetyl)-L-pipecolic Acid By substituting L-pipecolic acid for the L-proline in the procedure of Example 1, 1-(2-benzoylthioacetyl)-L-pipecolic acid is obtained.
Example 10 1-(2-Mercaptoacetyl)-L-Pipecolic Acid By treating the product of Example 9 with ammonia as in Example 2, 1-(2-mercaptoacetyl)-L-pipecolic acid is obtained.
Example 11 1-(2-Benzoylthiopropanoyl)-L-Proline L-Proline (5.75 g.) is dissolved in aqueous N so-dium hydroxide (50 ml.) and the solution is chilled in an ice bath with stirring. 2N sodium hydroxide (25 ml.) and 2-bromopropionyl chloride (8.57 g.) are added in that order and the mixture is removed from the ice bath and stirred at room temperature for one hour. A mixture of thiobenzoic acid (7.5 g.) and potassium carbonate (4.8 g.) in water (50 ml.) is added and the mixture is stirred over-night at room temperature. After acidification with con-centrated hydrochloric acid, the aqueous solution is ex-tracted with ethyl acetate and the organic phase is washed with water, dried and concentrated to dryness. The residue (14.7 g.) is chroma-tographed on a column of 440 g. of silica gel with a mix-ture of benzene-acetic acid (7:1). The fractions contain-ing the desired material are pooled, concentrated to dry-ness, and the residue is precipitated twice wi-th ether-hexane and converted to a dicyclohexylamine salt in ether-hexane, yield 9.4 g. m.p., (142) 148-156. The dicyclo-hexylamine salt is converted back to the acid as in Exam-ple 1, yield 5.7 g.
Example 12 1-(2-Mercaptopropanoyl)-L-Proline 1-(2-Benzoylthiopropanoyl)-L-proline (5.7 g.) is dissolved in a mixture of water (12 ml.) and concentrated ammonium hydroxide (9 ml.) with stirring. After one hour, the mixture is diluted with water (10 ml.) and filtered.
The filtrate is extracted twice with ethyl acetate, con-centrated to one-third of the original volume, acidified with concentrated hydrochloric acid and extracted with ethy7 acetate. The organic phase is washed with satura-ted sodium chloride, dried a`nd concentrated to dryness invacuo. The residue, 1-(2-mercaptopropanoyl)-L-proline, is crystallized from ethyl acetate-hexane, yield 3 g., m.p.
(105) 116-120. , Example 13 1-(3-Benzoylthiopropanoyl)-L-Proline L-Proline (5.75 g.) is dissolved in normal sodium hydroxide (S0 ml.) and the solution is chilled in an ice bath. 3-Bromopropionyl chloride (~.5 g.) and 2N sodium hydroxide (27 ml.) are added and the mixture is stirred for 10 minutes in the ice bath and three hours at room temperature. A suspension of thiobenzoic acid (7.5 g.) and potassium carbonate (4.5 g.) in water (50 ml.) is added and the mixture is stirred -~ ~, -22-, for 18 hours at room temperature. After acidification with concentrated hydrochloric acid, the aqueous phase is ex-tracted twice with ethyl acetate. The organic layers are dried over magnesium sulfate and concentrated to dryness in vacuo to obtain l-(3-benzoylthiopropanoyl)-L-proline, yield 7.1 g., m.p. 101-102 (ethyl acetate-hexane).
Example 14 L-Proline tert.-butyl ester L-Proline (230 g.) is dissolved in a mixture of water (1 1.) and 5 ~ sodium hydroxide (400 ml.). The so-lution is chilled in an ice bath, and under vigorous stir-ring, 5 N sodium hydroxide (460 ml.) and benzyloxycarbonyl chloride (340 ml.) are added in five equal aliquots during a half hour period. After one hour stirring at room tem-perature, the mixture is extracted twice with ether and acidified with concentrated hydrochloric acid. The preci-pitate is filtered and dried. Yield 442 g., m.p. 78-80.
The benzyloxycarbonyl-L-proline thus obtained (180 g.) is dissolved in a mixture of dichloromethane (300 ml.), liquid isobutylene (800 ml.) and concentrated sulfuric acid t7.2 ml.). The solution is shaken in a pressure bottle for 72 hours. The pressure is released, the isobutylene is allowed to evaporate and the solution is washed with 5%
sodium carbonate, water, dried over magnesium sulfate and concentrated to dryness in vacuo, to obtain benzyloxycar-bonyl-L-proline tert. butyl ester, yield 205 g.
Benzoyloxycarbonyl-L-proline tert. butyl ester (205 g.) is dissolved in absolute ethanol (1.2 1) and hy-drogenated at normal pressure with 10% Pd on carbon (10 g.) until only a trace of carbon dioxide is observed in the hydrogen exit gas '' (24 hours). The catalyst is filtered off and the filtrate is concentrated in vacuo a-t 30 mm. ~Ig. The residue is distilled in vacuo, to obtain L-proline tert.bu-tyl es-ter, b p 5Q-51.
lmm Example 15 1-(3-Acetylthiopropanoyl)-L-Proline tert-butyl Ester L-Proline tert-butyl ester (5.13 g.) is dissolved in dichloromethane (40 ml.) and the solution is chilled in an ice-water bath. A solution of dicyclohexylcarbodiimide (6.18 g.) in dichloromethane (20 ml.) is added followed immediately by 3-acetylthiopropionic acid (4.45 g.).
After 15 minutes stirring in the ice-water bath and 16 hours at room temperature, the precipitate is filtered off and the filtrate is concentrated to dryness in vacuo.
The residue is dissolved in ethyl acetate and washed neu-tral. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo to obtain 9.8 g. of 1-(3-acetylthiopropanoyl)-L-proline tert-butyl ester.
Example 16 1-(3-Acetylthiopropanoyl)-L-Proline 1-(3-Acetylthiopropanoyl)-L-proline-t-butyl ester (4.7 g.) is dissolved in a mixture of anisole (34 ml.) and trifluoroacetic acid (68 ml.) and the mixture is kept at room temperature for one hour. The solvents are removed in vacuo and the residue is precipitated from ether-hexane several times. The residue (3.5 g.) is dis-solved in acetonitrile (25 ml.) and dicyclohexylamine (2.8 ml.) is added. The crystalline salt is filtered and recrystallized from isopropanol. Yield 3.8 g.. m.p.
176-177Q. The saLt is reconverted to 1-(3-acetylthio-propanoyl)-L-prol:ine as in Example 1, yield 1.25 g., m.p. 89-90 ~ethyl ace-tate-hexane).
Example 17 1-(3-~lercaptopropanoyl)-L-prollne tert-bu-tyl E.ster To a solution of L-proline tert-bu-tyl es-ter (3.42 g.) in dry tetrahydrofuran (10 ml.) chilled in an ice bath, propiothiolactone (1.76 g.) is added. After 5 minutes storage in the ice bath and three hours at room ~emperature, the reaction mixture is diluted with ethyl acetate (200 ml.) and washed with 5% potassium bisulfate, and water.
The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue 1-(3-mer-captopropanoyl)-L-proline tert-butyl ester is crystallized from ether-hexane, yield 3.7 g., m.p. 57-58.
Example 18 1-(3-Mercaptopropanoyl)-L-Proline Procedure A
1-(3-Benzoylthiopropanoyl)-L-proline (4.9 g.) is dissolved in a mixture of water (8 ml.) and concentrated ammonium hydroxide (5.6 ml.) and the solution is stored with stirring under argon for one hour. The reaction mix-ture is diluted with water, filtered, and the filtrate is extracted with ethyl acetate. The aqueous phase is acid-ified with concentrated hydrochloric acid, saturated with sodium chloride and extracted with ethyl acetate. The organic layers are washed with saturated sodium chloride, dried over magnesium sulfate, and concentrated to dryness in vacuo. The residue, 1-(3-mercaptopropanoyl)-L-proline, is crystallized from ethyl acetate hexane, yield 2.5 g., m.p. 68-70~.
Procedure B
1-(3-Acetylthiopropanoyl)-L-proline (0.8 g.) is dis-solved ~ r ~ ~,~?~
in 5.5 N methanolic ammonia (5 ml.) and the solution kep-t under argon at room temperature. After 2 hours the solvent is removed in vacuo, the residue is dissolved in water and applied -to an ion exchange column on the H cycle [Dowex 50 (Analytical grade)] and eluted with water. The fractions that give thiol positive reaction are pooled and concentra-ted to dryness, yield 0.6 g. This product is crystallized from ethyl acetate-hexane as in Procedure A to obtain 1-(3-mercaptopropanoyl)-L-proline.
Procedure C
1-(3-Mercaptopropanoyl)-L-proline t-butyl ester (2.3 g.) is dissolved in a mixture of anisole (20 ml.) and tri-fluoroacetic acid (45 ml.). After one hour storage at room temperature under argon, the reaction mixture is con-centrated to dryness in vacuo and the residue precipitated from ethyl acetate-hexane several times. The residue (1.9 g.) is dissolved in ethyl acetate (30 ml.) and di-cyclohexylamine (1.85 ml.) is added. The crystalline salt is filtered and recrystallized from isopropanol, yield , 2 g., m.p. 187-188.
The salt is converted to the acid as in Example 1, yield 1.3 g. The product is crystallized from ethyl ace-tate hexane as in Procedure A.
Salts Sodium 1-(3-Mercaptopropanoyl)-L-proline (500 mg.) is dis-solved in a mixture of water (2.5 ml.) and N sodium hy-droxide (2.5 ml.). The solu-tion is freeze dried to ob-tain the sodium salt.
Maqnesium -1-(3-Mercaptopropanoyl)-L-proline (500 mg.), mag-nesium oxide (49.5 mg.), and water (10 ml.) are stirred ~ -26-with slight heatin~ until complete solution is obtained.
Then the solvent is removed by freeze drying to obtain the magnesium salt.
Calcium 1-(3-Mercaptopropanoyl)-2-proline (500 mg.) is dissolved in a mixture of calcium hydroxide (91 mg.) and water (10 ml.), and the solution is Ereeze dried to obtain the calcium salt.
Potassium 1-(3-Mercaptopropanoyl)-L-proline (500 mg.) is dissolved in a mixture of potassium bicarbonate (246 mg.) -and water (10 ml.) and freeze dried to obtain the potassium salt.
N-Methyl-D-Glucamine 1-(3-Mercaptopropanoyl)-L-proline(500 mg.) and N-methyl-D-glucamine (480 mg.) are dissolved in water (10 ml.) and freeze dried to obtain the N-methyl-D-glucamine salt.
Example 19 1-(3-Mercaptopropanoyl)-L-Hydroxyproline ~`
By substituting L-hydroxyproline for the L-proline in the procedure of Example 11 and then treating the pro-duct by Procedure A of Example 18, 1-(3-benzoylthiopropan-oyl)-L-hydroxyproline and 1-(3-mercaptopropanoyl)-L-hydr-oxyproline, respectively, are obtained.
Example 20 1-(3-Mercaptopropanoyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid tert-butyl ester (prepared by substituting L-azetidine-2-carboxylic acid ~or the proline in Example 14) for the L-proline tert-butyl ester in the procedure of Example 15, , .
treating the product as in Example 16 and the 1-(3-acetyl-thiopropanoyl)-L-azetidine-2-carboxylic acid thus ob-tained by Procedure B of Example 18, 1-(3-acetylthiopropanoyl)-L-azetidine-2-carboxylic acid tert-butyl ester and 1-(3-mercaptopropanoyl)-L-azetidine-2-carboxylic acid, respec-tively, are obtained.
Example 21 1-(3-Mercaptopropanoyl)-L-Pipecolic Acid By substituting L-pipecolic acid tert-butyl ester (prepared by substituting L-pipecolic acid for -the L-pro-line in Example 14) for the L-proline tert-butyl ester in the procedure of Example 15 and treating the product by Procedure C of Example 18, 1-(3-mercaptopropanoyl)-L-pipecolic acid tert-butyl ester and l-(3-mercaptopropan-oyl)-L-pipecolic acid, respectively, are obtained.
Example 22 1-(3-Mercaptopropanoyl)-4-Methyl-L-Proline By substituting 4-methyl-L-proline for L-proline in the procedure of Example 13 and then treating the product by Procedure A of Example 18, 1-(3-benzoylthiopropanoyl)-4-methyl-L-proline and 1-(3-mercaptopropanoyl)-4-methyl- ~.
L-proline, are obtained.
Example 23 1-(3-Mercaptopropanoyl)-5-Hydroxy-L-Pipecolic Acid By substituting 5-hydroxy-L-pipecolic acid for L-proline in the procedure of Example 13 and then treating the product by the Procedure A of Example 18, 1-(3-ben-zoylthiopropanoyl)-5-hydroxy-L-pipecolic, and 1-(3-mercaptopropanoyl~-5-hydroxy-L-pipecolic acid are obtained.
Example 24 1-(3-Mercaptopropanoyl)-D-Proline By substituting D-proline for L-proline in the pro-cedure of Example 13 and then treating the product by Pro-cedure A of Example 18, 1-~3-benzoy]thiopropanoyl)-D-proline and 1-(3-mercaptopropanoyl)-D-proline, m.p. 68-70, are ob--tained.
Example 25
The products of formula I and the preferred subgroups can be produced by various methods of synthesis.
In general, the products-of this invention are produced by acylating a compound of the formula ~III) H2C-- (Cll)m ~ N Cll - COR
with an acid of the formula (IV) R~ R
2 ( )n _ ,j_ ~ 3Al35b or its chemical equivalent.
Thus, the final product can be produced not only by direct acylation ~ith an acid of forrnula IV but also by intermediates such as ~a) ~-haloalkanoic acids of the formula R4 Rl (V) l I
X - (CH)n-- - CH - COOH
wherein X is bromo, chloro or iodo, or (b) a tosyloxyalkanoic acid, i.e., X in formula V is tosyloxy (CH3 ~ SO2O-) (c) a substituted acrylic acid of the formula 14 1l (VI) CH - C COOH
The product of this acylation is then subjected to displacement or addition with the anion of a thiol or thioacid of the formula (VII) R2 SH
Acylation can also be effected with a thiolactone of the formula IR4 IRl l (VIII) (fH) -- fH
S =O
wherein n is l or 2, or a mercaptoalkanoic acid of the formula (IX) ~ )n COR
I-IA135b wherein Y is ~ or, in aclclition, i~ a produc~ of formula I
wherein R2 is hydrogen is desired, then Y can also be a protecting group such as (a)RlC~l3O~ CH2 , ( ) ~
(c) CH3CONHCH2, (d) I~-O-C-C~I-(C~-I) -S- or other sulfur protectinc3 group. "Deprote~ction" can be effected by eonventional means sueh as treatment with hot trifluoroacetic aeid, cold trifluoromethanesulfon:ic aeid, mercuric acetate, sodium in liquid ammonia, zinc and hydrochloric acid or the like. For a review of these methods see Methoden der Organisehen Chemie (Houben-Weyl), Vol. XV, part I, page 736 et seq. (1974).
When the acid of formula IV is used as the aeylating agent, the aeylation can be effeeted in the presence of a eoupling agent like dicyelohexyearbodiimide or the like, or the aeid ean be aetivated by formation of its mixed annydride, symmetrieal anhydride, aeid chloride, acid ester or use of Woodward reagent K, N-ethoxyearbonyl-2-ethoxy-1,2-dihydroquinoline or the like. For a review of the methods for aeylation, see Methoden der Organischen Chemie (Houben-Weyl), Vol. XV, part II, page 1 et seq. (1974).
Compounds of formula III include, for example, proline, hydroxyproline, 4-methylproline, pipeeolic acid, 5-hydroxypipecolie aeid, azetidine-2-carboxylic acid, their lower alkyl esters and the like. The aeylation of sueh compounds is described in greater detail below.
According to a preferred method for producinc3 compounds oî formula I, espeeially wherein R2 is r~5-CO-, an acid or ester of formula III is coupled with a haloalkanoic acid of the formula ~:f~
HAl35b (V) R R
14 1l ;
( )n ~herein X is a haloc3ell, prcferably chlorine or bromine. This can be effectecl by one of the known procedures in which the acid IV is activated, prior to reaction ~ith the acid III, involving formation of a mixed anhydride, symmetrical anhydride, acid chloride, active estcr, or use of Woodward reayent K, EEDQ
(N-ethoxycarbonyl-2-ethoxy-l,2-dihydroxyquinoline) or the like.
The product of this reaction is a compound of the formula (X) IR3 - 14 1l H2C - (CH) X - (C11) - C~1- CO - N C~1-COR
The product of formula X is subjected to a displaccmcnt reaction with the anion of a thioacid of the formula (VII) R2-S~I
yielding a product of the formula (XI) IR3 ,`
14 ~ 2C- (C~l)m R2- S - (C1~ C~l-CO - N - CII-COR
When R2 is R5CO, this product can thcn bc converted to the product (XII) R3 R4 ~ 2C (C11)m i-lS - (C11) - CH - CO - N CH-COR
by ammonolysis. When R2 is a protecting group, -then the compound of formula XII can be ob-tained by "depro-tec-tion"
as described above. When R is an ester group (i.e., R is lower alkoxy), the ester group can be removed, e.g., when R is tert. butoxy or tert. amyloxy, by trea-tment of the ester of formula XI or XII wi-th trifluoroacetic acid and anisole to give the corresponding free acid. When o-ther alkoxy groups are present, alkaline hydrolysis will yield the corresponding acid.
A variation of this procedure involves the use of an acrylic acid of 'he formula ~VI) R4 Rl CH=C-COOH
as starting material. This acrylic acid is first conver-ted to the acid halide form then made to react with a compound of formula III to obtain a compound of the for-mula R3 (XIII) IR4 IRl H2CI (CH)m CH=C - CO - N CH-COR
and this intermediate is subjected to the addition reac-tion with the thiol or thioacid VII as described above.
A tosyloxyalkanoic acid of the formula (XIV) IR4 IRl CH3- ~ _ S020-(CH)n CH - COOH
can also be used as the agent to acylate the acid of formula III, then the acylation product is subjected to the displacement reaction, etc., as described above.
The acrylic acid of formula VI can alternatively be firs-t made to react with the thioacid of formula VII to ' obtain a product of the formula (XV) R14 IRl which is converted to i-ts acid halide, e.g., with thionyl chloride, then coupled to the compound of formula III and the same sequence as above then followed.
The acid or ester of formula III can also be acylated with a "protected" form of a ~-mercaptoalkanoic acid of the formula (XVI) 4 R8-s-(cH)n-cH-cooH
wherein R8 is the "protecting" group. Such "protecting"
groups can take the form described above.
Following the acylation, the product can be "depro-tected" by one of the known methods referred to above.
Still another acylating agent can take the form of a thiolactone, e.g., ~-propiothiolactone, N-methyl-~-pro-piothiolactone or the like.
Additional details of preferred modes of producing compounds of this invention can be found in the following and in the specific examples.
According to a particularly preferred modification, the acid or ester of formula III is acylated with a halo-alkanoyl halide of the formula (XVII) 14 1l X-(CH)n CH-COX
wherein each X is independently a halogen, preferably chlorine or bromine, Rl is hydrogen, lower alkyl or phenyl-lower alkyl .~ . . . .
J' ~S~
and n is 0, 1 or 2. This r~action is effected in an alka-line medium, e.g., dilute alkali metal hydroxide solution, alkali metal dicarbonate or alkali metal carbona-te solution at a reduced temperature, e.g., about 0 to 15C. The re-action product is subjected to displacement with the anion of the thiol or thio acid of the formula VII above, also in alkaline medium, preferably alkali metal carbonate so-lution, and then worked up in conventional manner. The product of this reaction, wherein R2 of formula I is R5-CO, is converted to the product wherein R2 is hydrogen by ammonolysis, e.g., alcoholic ammonia or concentrated ammonium hydroxide solution, or alkaline hydrolysis, e.g., with aqueous metal hydroxide. When an acid of formula III is used as starting material, the final product ob-tained as the free carboxylic acid can then be converted to its ester, for example by esterification with a dia-zoalkane, like diazomethane, l-alkyl-3-p-tolyl-triazene, like l-n-butyl-3-p-tolyltriazene or the like. Treatment of an ester, preEerably the methyl ester, with an alco-holic ammonia solution, converts the free acid to theamide, i.e., R is NH2.
According to another variation, an ester, prefer-ably the t-butyl ester, of formula III, in an anhydrous medium such as dichloromethane, tetrahydrofuran, dioxane or the like, is treated with a thioalkanoic acid of the formula (XVIII) IRl R2-S-(CH2)n ---- CH - COOH
in the presence oE dicyclohexylcarbodiimide, N,N'-car-bonyl-bisimidazole, ethoxyacetylene, diphenylphosphoryl azide or similar coupling agents at a temperature in the range of about 0 to 10C. The ester group (R) can then be removed, for ;2 5~
example, by treatment with trifluoroacetic acid and ani-sole at about room temperature.
When an ester of formula III (e.g., R is lower al-koxy, especially, t-butoxy) is acylated with a thiolactone, e.g., ~-propiothiolactone, ~-methyl-~-propiothiolactone or the like, the reaction can be effected in an anhydrous solvent like tetrahydrofuran, dioxane, methylene chloride or the like at about 0 C. to about room temperature. The ester group can be removed with anisole and trifluorace-tic acid as described above. M
In similar manner, when R2 is R5-M-C-, products of formula I having this substituent are formed by reacting a compound of formula XII with the halogenated compound ~XIX) M
or alternatively reacting a compound of formula X with an alkali metal salt or alkaline earth metal salt of the formula tXX) M
R5-M-C-S-Me wherein Me represents the alkali metal or alkaline earth metal. M
.
~ hen R2 is R5-NH-C-, products of formula I having this substituent are produced by reacting a compound of formula XII with the appropriately substituted isocyanate or isothiocyanate of the formula (XXI) R5-N=C=M
Alternatively, the same products can be produced by coup-ling an acid of the formula ~- -12-,.~
IIA 1 3 5 b ( .`;X I I ) M R R
R5-NEI-C-S- (CE~)-- CH-COOEI
with an amino acid of formllla IlI.
Compounds of formula I, wilerein R2 is lower alkyl, phenyl, substituted phenyl, phenyl-lower alkyl, -triphenyl-lower alkyl, lower alkylthiomethyl or phenyl-lower alkylthiomethyl are produced by reacting a compound of formula XII with the corresponding halide R~X or ~y reacting a compound of formula X
with the corresponding thiol R2SH in the same manner as described above.
When R2 is lower alkanoylamidomethyl, the product of formula I is produced by condensing a compound of formula XII
with the corresponding hydroxymethyl-lower alkanoylamide of the formula ~XXIII) lower alkyl-CO-NHCH2OH
in the presence of an acid catalyst like trifluoroacetic acid.
Products of formula I wherein R2 is R6-S can be prepared by any of the known methods for the synthesis of mixed disulfides, e.g., by the reaction of a compound of formula(XII)with a thiosulfinate(xxIv), thiosulfonate (XXV), sulfenyl halide (XXVI), thiosulfate (XXVII) or sulfenyl thiocyanate (XXVIII) O
(XXIV) R6-S-S-R6, (XXV) R6-S-S-R6, (XXVI) R6S-X, O
(XXVII) R6-S-S03H, (XXVIII) R6-S-SCN
In the particular case wherein R7 is R R CEE -- (CH) 14 1l 1 2 1 n -S (O) ---- (CE~ CH-- CO-- N -- CH-COR, s~
~IA135b R, R , R3 and R4 are the same as the corresponding substituents in formula I and p is O, the symmetrical disulfides can be obtained by direct o~cidation of a compound of formula XII
with iodine. ~hen p is 1 or 2, such products are obtained by the stepwise oxidation of the corresponding compound wherein p is O. Mixed disulfides are obtained by the modification shown in the examples.
Products of formula I have one or more asym~etric carbons.
When Rl, R3 or R4 is other than hydrogen the carbon to which it is attached is asymmetric. These carbon atoms are indicated by an asterisk in formula I. The compounds accordingly exist in stereoisomeric forms or in racemic mixtures thereof. All of these are within the scope of the invention. The above described synthesis can utilize the racemate or one of the enantiomers as starting material.
~hen the racemic starting material is used in the synthetic procedure, the stereoisomers obtained in the product can be separated by conventional chromatographic or fractional crystallization methods. In general, the L-isomer with respect to the carbon of the amino acid constitutes the preferred isomeric form. Also the D-isomer with respect to the a-carbon in the acyl side chain (i.e., the carbon bearing Rl) is preferred.
The com~ounds of this invention form basic salts with various inorganic and organis bases which are also within the scope of the invention. Such salts include ammonium salts, alkali metal salts like sodium and potassium salts (which are preferred), alkaline earth metal salts like the calcium and magnesium salts, salts with organic bases, e.g., dicyclohexylamine salt, benzathine, N-methyl-D-glucamine, --1~--.. ..
~-IA135b hydrabamine salts, salts with amino acids like arginine, lysine and the like. The non-toxic, physiologically acceptable salts are preferred, although other salts are also useful, e.g., in isolating or purifyincJ the procluct, as illustrated in the examples in the case of tne dicyclohexylamine salt.
The salts are formed in conventional manner by reacting the free acid form of the product with one or more equivalents of the appropriate base providing the desired cation in a solvent or medium in which the salt is insoluble, or in ~ater and removing the water by freeze drying. By neutralizing the salt with an insoluble acid like a cation exchange resin in the hydrogen form (e.g., polystyrene sulfonic acid resin like Dowex 50) or with an aqueous acid and extraction with an organic solvent, e~g., ethyl aceta-te, dichloromethane or the like, the free acid form can be obtained, and, if desired, another salt formed.
~ dditional experimental details are found in the examples which are preferred embodiments and also serve as models for -the preparation of other members of the group.
The compounds of this invention inhibit the conver-sion of the decapeptide angiotensin I to angiotensin II
and therefore are useful in reducing or relieving angio-tensin related hypertension. The action of the enzyme re-nin on angiotensinoqen, a pseudoglobulin in blood plasma, produces angiotensin I. Angiotensin I is converted by angiotensin converting enzyme (ACE) to angiotensin II.
The latter is an active pressor substance which has been implicated as the causative agent in various forms of hypertension in various mammalian species, e.g., rats and dogs. The compounds of this invention intervene in the angiotensin(renin)~angiotensin I ~angiotensin II sequence by inhibiting angiotensin converting enzyme and reducing or eliminating the formation of the pressor substance angiotensin II. Thus by the administration of a composi-tion containing one or a combination of compounds of for-mula I or physiologically acceptable salt thereof, angio-tensin dependent hypertension in the species of mammal suffering therefrom is alleviated. A single dose, or pre-ferably two to four divided daily doses, provided on a basis of about 0.1 to 100 mg. per kilogram per day, pre-ferably about 1 to 50 mg. per kilogram per day is appro-priate to reduced blood pressure as indicated in the ani-mal model experiments described by S.L. Engel, T.R.
Schaeffer, M.H. Waugh and B. Rubin, Proc. Soc. Exp. Biol.
Med. 143, 483 (1973). The substance is preferably admin-istered orally, but parenteral routes such as subcutaneous,intramuscular, intravenous or ~i .
5~
intraperitoneal can also be employed.
The compounds of this invention can be utilized to achieve the reduction of blood pressure by forn~lating in compositions such as tablets, capsules or elixirs for oral administration or in sterile solutions or suspensions for parenteral aclministration. About 10 to 500 mg. of a compound or mixture of compo~mds of formula I or physio-logieally acceptable salt is compounded with a physiologically aecep-table vehiele, carrier, excipient, binder, preservative, stabilizer, flavor, ete., in a unit dosage form as called for by accepted phar-maceutieal practice. The amount of active substance in these com-positions or preparations is such that a suitable dosage in the range indieated is obtained.
Illustrative of the adjuvants which may be incorporated in tablets, capsules and the like are the follcwing: a binder such as gum tragacanth, aeaeia, eorn stareh or gelatin; an exeipient such as diealeium phosphate; a disintegrating agent such as corn stareh, potato stareh, alginie aeid and the like; a lubrieant sueh as magnesium stearate; a s~eetening agent sueh as suerose, laetose or saeeharin; a flavoring agent such as peppermint, oil of winter-green or eherry. When the dosage unit form is a eapsule, it mayeontain in addition to materials of the above type a liquid earrier such as a fatty oil. Various other materials may be present as eoatings or to otherwise modify the physieal form of the dosage unit. For instanee, tablets may be eoated with shellae, sugar or both. A syrup or elixir may eontain the aetive compound, suerose as a sheetening agent, methyl and propyl parabens as preservatives, a dye and a flavorinq sueh as cherry or orange flavor.
Sterile eom~sitions for injeetion ean be formulated .
~3~5~
according -to conventional ~harmaceutical praetiee by dis-solving or suspending the active substance in a vehicle such as water for injection, a naturally occurring vege-table oil like sesame oil, coconut oil, peanut oil, cotton-seed oil, ete., or a synthetic fatty vehicle like ethyl oleate or the like. Buffers, preservatives, antioxidants and the like ean be ineorporated as required.
The following examples are illustrative of the in-vention and eonstitute espeeially preferred embodiments.
All temperatures are in degrees celsius.
. .,. ,~ _ -E:;ample 1 senzoylthioacetyl)-L-Proline L-Proline (5.75 q.) is dissolved in N sodium hydr-oxide (50 ml.) and the solution is chilled in an ice-water bath. Sodium hydroxide 2N (26 ml.) and chloroacetyl chlo-ride (5.65 g.) are added and the mixture is stirred vigo-rously at room temperature for three hours. A suspension of thiobenzoic acid (7.5 g.) and potassium carbonate (4.8 g.) in water (50 ml.) is added. After 18 hours stirring a~ room temperature, the reaction mixture is acidified and extracted with ethyl acetate. The ethyl acetate layer is washed with water, dried over magnesium sulfate and con-centrated to dryness in vacuo. The residue (14.6 g.) is dissolved in ethyl acetate (150 ml.) and dicyclohexylamine ~ -(11 ml.) is added. The crystals are filtered and recry-stallized from ethyl acetate, yield 5.7 g. m.p. 151-152.
To convert the salt to the acid, the crystals are dissol-vea in a mixture of 5~ aqueous potassium bisulfate (100 ml.) and ethyl acetate (300 ml.). The organic phase is washed once with water, dried over magnesium sulfate and concentrated to dryness in vacuo, yield 3.45 g.
Example 2 1-(2-Mercaptoacetyl)-~-Proline 1-(2-Benzoylthioacetyl)-L-proline (3.4 g.) is dis-solved in a mixture of water (10.5 ml.) and concentrated ammonia (6.4 ml.). After one hour, the reaction mixture is diluted with water and filtered. The ~iltrate is ex-tracted with ethyrl acetate and then acidified with con-centrated hydrochloric acid, saturated with sodium chlo-ride and extracted twice with ethyl acetate. The ethylacetate extracts are washed with saturated sodium chlo-ride and concentrated to dryness, yield 1.5 g.
Tne product, 1-(2-mercaptoacetyl)-L-proline is crystallized from ethyl acetate (m.p. 133-135).
Example 3 1-(2-Benzoylthioacetyl)-L-Proline Methyl Ester 1-(2-Benzoylthioacetyl)-L-proline obtained in Example 1, is dissolved in methanol and an ethereal solution of diazomethane is added until there is a persistent yellow color. ~fter 15 minutes, a few drops of acetic acid are added and the solvent is removed in vacuo to obtain l-t2-benzoylthioacetyl)-L-proline methyl ester.
Example 4 1-(2-Mercaptoacetyl)-L-Proline Amide The product of Example 3 is dissolved in 10~ metha-nolic ammonia and the solution is stored at room tempera-ture in a pressure bottle. When thin layer chromatogra-phic analysis indicates that the two ester functions have been ammonolyzed, the reaction mixture is concentrated to dryness to obtain l-(2-mercaptoacetyl)-L-proline amide.
Example 5 1-~2-Benzoylthioacetyl)-L-Hydroxyproline By substituting L-hydroxyproline for the L-proline in the procedure of Example 1, 1-(2-benzoylthioacetyl)-L-hydroxyproline is obtained.
Example 6 1-(2-Mercaptoacetyl)-L-Hydroxyproline By treating the product of Example 5 with ammonia as in Example 2, 1-(2-mercaptoacetyl)-L-hydroxyproline is obtained.
Example 7 1-(2-Benzoylthioacetyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid for the `~
- ~ .
.3~
L-proline in the procedure of Example 1, 1-(2-benzoylthio-acetyl)-L-azetidine-2-carboxylic acid is ob-tained.
Example 8 1-(2-Mercaptoacetyl)-L-Azetidine-2-Carboxylic Acid By treating the product of ~xample 7 with ammonia as in Example 2, 1-(2-mercaptoacetyl)-L-azetidine-2-car-boxylic acid is obtained.
Example 9 1-(2-Benzoylthioacetyl)-L-pipecolic Acid By substituting L-pipecolic acid for the L-proline in the procedure of Example 1, 1-(2-benzoylthioacetyl)-L-pipecolic acid is obtained.
Example 10 1-(2-Mercaptoacetyl)-L-Pipecolic Acid By treating the product of Example 9 with ammonia as in Example 2, 1-(2-mercaptoacetyl)-L-pipecolic acid is obtained.
Example 11 1-(2-Benzoylthiopropanoyl)-L-Proline L-Proline (5.75 g.) is dissolved in aqueous N so-dium hydroxide (50 ml.) and the solution is chilled in an ice bath with stirring. 2N sodium hydroxide (25 ml.) and 2-bromopropionyl chloride (8.57 g.) are added in that order and the mixture is removed from the ice bath and stirred at room temperature for one hour. A mixture of thiobenzoic acid (7.5 g.) and potassium carbonate (4.8 g.) in water (50 ml.) is added and the mixture is stirred over-night at room temperature. After acidification with con-centrated hydrochloric acid, the aqueous solution is ex-tracted with ethyl acetate and the organic phase is washed with water, dried and concentrated to dryness. The residue (14.7 g.) is chroma-tographed on a column of 440 g. of silica gel with a mix-ture of benzene-acetic acid (7:1). The fractions contain-ing the desired material are pooled, concentrated to dry-ness, and the residue is precipitated twice wi-th ether-hexane and converted to a dicyclohexylamine salt in ether-hexane, yield 9.4 g. m.p., (142) 148-156. The dicyclo-hexylamine salt is converted back to the acid as in Exam-ple 1, yield 5.7 g.
Example 12 1-(2-Mercaptopropanoyl)-L-Proline 1-(2-Benzoylthiopropanoyl)-L-proline (5.7 g.) is dissolved in a mixture of water (12 ml.) and concentrated ammonium hydroxide (9 ml.) with stirring. After one hour, the mixture is diluted with water (10 ml.) and filtered.
The filtrate is extracted twice with ethyl acetate, con-centrated to one-third of the original volume, acidified with concentrated hydrochloric acid and extracted with ethy7 acetate. The organic phase is washed with satura-ted sodium chloride, dried a`nd concentrated to dryness invacuo. The residue, 1-(2-mercaptopropanoyl)-L-proline, is crystallized from ethyl acetate-hexane, yield 3 g., m.p.
(105) 116-120. , Example 13 1-(3-Benzoylthiopropanoyl)-L-Proline L-Proline (5.75 g.) is dissolved in normal sodium hydroxide (S0 ml.) and the solution is chilled in an ice bath. 3-Bromopropionyl chloride (~.5 g.) and 2N sodium hydroxide (27 ml.) are added and the mixture is stirred for 10 minutes in the ice bath and three hours at room temperature. A suspension of thiobenzoic acid (7.5 g.) and potassium carbonate (4.5 g.) in water (50 ml.) is added and the mixture is stirred -~ ~, -22-, for 18 hours at room temperature. After acidification with concentrated hydrochloric acid, the aqueous phase is ex-tracted twice with ethyl acetate. The organic layers are dried over magnesium sulfate and concentrated to dryness in vacuo to obtain l-(3-benzoylthiopropanoyl)-L-proline, yield 7.1 g., m.p. 101-102 (ethyl acetate-hexane).
Example 14 L-Proline tert.-butyl ester L-Proline (230 g.) is dissolved in a mixture of water (1 1.) and 5 ~ sodium hydroxide (400 ml.). The so-lution is chilled in an ice bath, and under vigorous stir-ring, 5 N sodium hydroxide (460 ml.) and benzyloxycarbonyl chloride (340 ml.) are added in five equal aliquots during a half hour period. After one hour stirring at room tem-perature, the mixture is extracted twice with ether and acidified with concentrated hydrochloric acid. The preci-pitate is filtered and dried. Yield 442 g., m.p. 78-80.
The benzyloxycarbonyl-L-proline thus obtained (180 g.) is dissolved in a mixture of dichloromethane (300 ml.), liquid isobutylene (800 ml.) and concentrated sulfuric acid t7.2 ml.). The solution is shaken in a pressure bottle for 72 hours. The pressure is released, the isobutylene is allowed to evaporate and the solution is washed with 5%
sodium carbonate, water, dried over magnesium sulfate and concentrated to dryness in vacuo, to obtain benzyloxycar-bonyl-L-proline tert. butyl ester, yield 205 g.
Benzoyloxycarbonyl-L-proline tert. butyl ester (205 g.) is dissolved in absolute ethanol (1.2 1) and hy-drogenated at normal pressure with 10% Pd on carbon (10 g.) until only a trace of carbon dioxide is observed in the hydrogen exit gas '' (24 hours). The catalyst is filtered off and the filtrate is concentrated in vacuo a-t 30 mm. ~Ig. The residue is distilled in vacuo, to obtain L-proline tert.bu-tyl es-ter, b p 5Q-51.
lmm Example 15 1-(3-Acetylthiopropanoyl)-L-Proline tert-butyl Ester L-Proline tert-butyl ester (5.13 g.) is dissolved in dichloromethane (40 ml.) and the solution is chilled in an ice-water bath. A solution of dicyclohexylcarbodiimide (6.18 g.) in dichloromethane (20 ml.) is added followed immediately by 3-acetylthiopropionic acid (4.45 g.).
After 15 minutes stirring in the ice-water bath and 16 hours at room temperature, the precipitate is filtered off and the filtrate is concentrated to dryness in vacuo.
The residue is dissolved in ethyl acetate and washed neu-tral. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo to obtain 9.8 g. of 1-(3-acetylthiopropanoyl)-L-proline tert-butyl ester.
Example 16 1-(3-Acetylthiopropanoyl)-L-Proline 1-(3-Acetylthiopropanoyl)-L-proline-t-butyl ester (4.7 g.) is dissolved in a mixture of anisole (34 ml.) and trifluoroacetic acid (68 ml.) and the mixture is kept at room temperature for one hour. The solvents are removed in vacuo and the residue is precipitated from ether-hexane several times. The residue (3.5 g.) is dis-solved in acetonitrile (25 ml.) and dicyclohexylamine (2.8 ml.) is added. The crystalline salt is filtered and recrystallized from isopropanol. Yield 3.8 g.. m.p.
176-177Q. The saLt is reconverted to 1-(3-acetylthio-propanoyl)-L-prol:ine as in Example 1, yield 1.25 g., m.p. 89-90 ~ethyl ace-tate-hexane).
Example 17 1-(3-~lercaptopropanoyl)-L-prollne tert-bu-tyl E.ster To a solution of L-proline tert-bu-tyl es-ter (3.42 g.) in dry tetrahydrofuran (10 ml.) chilled in an ice bath, propiothiolactone (1.76 g.) is added. After 5 minutes storage in the ice bath and three hours at room ~emperature, the reaction mixture is diluted with ethyl acetate (200 ml.) and washed with 5% potassium bisulfate, and water.
The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue 1-(3-mer-captopropanoyl)-L-proline tert-butyl ester is crystallized from ether-hexane, yield 3.7 g., m.p. 57-58.
Example 18 1-(3-Mercaptopropanoyl)-L-Proline Procedure A
1-(3-Benzoylthiopropanoyl)-L-proline (4.9 g.) is dissolved in a mixture of water (8 ml.) and concentrated ammonium hydroxide (5.6 ml.) and the solution is stored with stirring under argon for one hour. The reaction mix-ture is diluted with water, filtered, and the filtrate is extracted with ethyl acetate. The aqueous phase is acid-ified with concentrated hydrochloric acid, saturated with sodium chloride and extracted with ethyl acetate. The organic layers are washed with saturated sodium chloride, dried over magnesium sulfate, and concentrated to dryness in vacuo. The residue, 1-(3-mercaptopropanoyl)-L-proline, is crystallized from ethyl acetate hexane, yield 2.5 g., m.p. 68-70~.
Procedure B
1-(3-Acetylthiopropanoyl)-L-proline (0.8 g.) is dis-solved ~ r ~ ~,~?~
in 5.5 N methanolic ammonia (5 ml.) and the solution kep-t under argon at room temperature. After 2 hours the solvent is removed in vacuo, the residue is dissolved in water and applied -to an ion exchange column on the H cycle [Dowex 50 (Analytical grade)] and eluted with water. The fractions that give thiol positive reaction are pooled and concentra-ted to dryness, yield 0.6 g. This product is crystallized from ethyl acetate-hexane as in Procedure A to obtain 1-(3-mercaptopropanoyl)-L-proline.
Procedure C
1-(3-Mercaptopropanoyl)-L-proline t-butyl ester (2.3 g.) is dissolved in a mixture of anisole (20 ml.) and tri-fluoroacetic acid (45 ml.). After one hour storage at room temperature under argon, the reaction mixture is con-centrated to dryness in vacuo and the residue precipitated from ethyl acetate-hexane several times. The residue (1.9 g.) is dissolved in ethyl acetate (30 ml.) and di-cyclohexylamine (1.85 ml.) is added. The crystalline salt is filtered and recrystallized from isopropanol, yield , 2 g., m.p. 187-188.
The salt is converted to the acid as in Example 1, yield 1.3 g. The product is crystallized from ethyl ace-tate hexane as in Procedure A.
Salts Sodium 1-(3-Mercaptopropanoyl)-L-proline (500 mg.) is dis-solved in a mixture of water (2.5 ml.) and N sodium hy-droxide (2.5 ml.). The solu-tion is freeze dried to ob-tain the sodium salt.
Maqnesium -1-(3-Mercaptopropanoyl)-L-proline (500 mg.), mag-nesium oxide (49.5 mg.), and water (10 ml.) are stirred ~ -26-with slight heatin~ until complete solution is obtained.
Then the solvent is removed by freeze drying to obtain the magnesium salt.
Calcium 1-(3-Mercaptopropanoyl)-2-proline (500 mg.) is dissolved in a mixture of calcium hydroxide (91 mg.) and water (10 ml.), and the solution is Ereeze dried to obtain the calcium salt.
Potassium 1-(3-Mercaptopropanoyl)-L-proline (500 mg.) is dissolved in a mixture of potassium bicarbonate (246 mg.) -and water (10 ml.) and freeze dried to obtain the potassium salt.
N-Methyl-D-Glucamine 1-(3-Mercaptopropanoyl)-L-proline(500 mg.) and N-methyl-D-glucamine (480 mg.) are dissolved in water (10 ml.) and freeze dried to obtain the N-methyl-D-glucamine salt.
Example 19 1-(3-Mercaptopropanoyl)-L-Hydroxyproline ~`
By substituting L-hydroxyproline for the L-proline in the procedure of Example 11 and then treating the pro-duct by Procedure A of Example 18, 1-(3-benzoylthiopropan-oyl)-L-hydroxyproline and 1-(3-mercaptopropanoyl)-L-hydr-oxyproline, respectively, are obtained.
Example 20 1-(3-Mercaptopropanoyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid tert-butyl ester (prepared by substituting L-azetidine-2-carboxylic acid ~or the proline in Example 14) for the L-proline tert-butyl ester in the procedure of Example 15, , .
treating the product as in Example 16 and the 1-(3-acetyl-thiopropanoyl)-L-azetidine-2-carboxylic acid thus ob-tained by Procedure B of Example 18, 1-(3-acetylthiopropanoyl)-L-azetidine-2-carboxylic acid tert-butyl ester and 1-(3-mercaptopropanoyl)-L-azetidine-2-carboxylic acid, respec-tively, are obtained.
Example 21 1-(3-Mercaptopropanoyl)-L-Pipecolic Acid By substituting L-pipecolic acid tert-butyl ester (prepared by substituting L-pipecolic acid for -the L-pro-line in Example 14) for the L-proline tert-butyl ester in the procedure of Example 15 and treating the product by Procedure C of Example 18, 1-(3-mercaptopropanoyl)-L-pipecolic acid tert-butyl ester and l-(3-mercaptopropan-oyl)-L-pipecolic acid, respectively, are obtained.
Example 22 1-(3-Mercaptopropanoyl)-4-Methyl-L-Proline By substituting 4-methyl-L-proline for L-proline in the procedure of Example 13 and then treating the product by Procedure A of Example 18, 1-(3-benzoylthiopropanoyl)-4-methyl-L-proline and 1-(3-mercaptopropanoyl)-4-methyl- ~.
L-proline, are obtained.
Example 23 1-(3-Mercaptopropanoyl)-5-Hydroxy-L-Pipecolic Acid By substituting 5-hydroxy-L-pipecolic acid for L-proline in the procedure of Example 13 and then treating the product by the Procedure A of Example 18, 1-(3-ben-zoylthiopropanoyl)-5-hydroxy-L-pipecolic, and 1-(3-mercaptopropanoyl~-5-hydroxy-L-pipecolic acid are obtained.
Example 24 1-(3-Mercaptopropanoyl)-D-Proline By substituting D-proline for L-proline in the pro-cedure of Example 13 and then treating the product by Pro-cedure A of Example 18, 1-~3-benzoy]thiopropanoyl)-D-proline and 1-(3-mercaptopropanoyl)-D-proline, m.p. 68-70, are ob--tained.
Example 25
3-Acetylthio-2-Methylpropanoic Acid A mixture of thioacetic acid (50 g.) and methacry-lic acid (40.7 g.) is heated on the steam bath for one hour and then stored at room temperature for 18 hours. After conEirming by nmr spectroscopy that complete reaction of the methacrylic acid has been achieved, the reaction mix-ture -is distilled in vacuo and the desired 3-acetylthio-2-methylpropanoic acid is separated in the fraction with boiling point 128.5-131 (2.6 mmHg.), yield 64 g.
Example 26 3-Benzoylthio-2-Methylpropanoic Acid By substituting thiobenzoic acid for the thioace-tic acid in the procedure of Example 25, 3-benzoylthio-2-methylpropanoic acid is obtained.
Example 27 3-Phenylacetylthio-2-Methylpropanoic Acid By substituting thiophenylacetic acid for the thio-acetic acid in the procedure of Example 25, 3-phenylacetyl thio-2-methylpropanoic acid is obtained.
Example 28 1-(3-Ace-tylthio-2-methylpropanoyl)-L-Proline tert-butyl Ester L-Proline tert-butyl ester (5.1 g.) is dissolved in dichloromethane (40 ml.) and the solution stirred and chilled ~ ~ -29-.
in an ice bath. Dicyclohexylcarbodiimide (6.2 g.) dissolved in dichloromethane (15 ml.) is added followed immediately by a solution of 3-acetylthio-2-methylpropanoic acid (4.9 g.) in dichloromethane (5 ml.). A~ter 15 minutes stirring in the ice bath and 16 hours at room temperature, the precipi-tate is filtered off and the filtrate is concentrated to !
dryness in vacuo. The residue is dissolved in ethyl acet-ate and washed neutral. The organic phase is dried over magnesium sulfate and concentrated to dryness in vacuo.
The residue 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester is purified by column chromatography (silica gel-chloroform), yield 7.9 g.
Example 29 1-(3-Acetylthio-2-methylpropanoyl)-L-Proline Procedure A
The 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester of Example 28 (7.8 g.) is dissolved in a mixture of anisole (55 ml.) and trifluoroacetic acid (110 ml.). After one hour storage at room temperature the sol-vent is removed in vacuo and the residue is precipitatedseveral times from ether-hexane. The residue (6.8 g.) is dissolved in acetonitrile (40 ml.) and dicyclohexylamine (4.5 ml.) is added. The crystalline salt is boiled with fresh ~cetonitrile (100 ml.), chilled to room temperature and filtered, yield 3.8 g., m.p. (165) 187-188. This ma-terial is recrystallized from isopropanol [~]D-67 (C 1.4, EtOH). The crystalline dicyclohexylamine salt is suspen-ded in a mixture of 5% aqueous potassium bisulfate and ethyl acetate. The organic phase is washed with water and concentrated to dryness. The residue is crystallized from ethyl acetate-hexane to`yield the l-(3-acetyl-5~
thio-~-D-methylpropanoyl-L-proline, m.p. 83-85[~]D -162 ( c , 1 . 7 , E tO~).
Procedure B
3-Acetylthio-2-methylpropanoic acid (8.1 g.) and thio-nyl chloride ( 7 g . ) are mixed and the suspension is stirred for 16 hours at room temperature. The reaction mixture is concentrated to dryness and distilled in vacuo ~b.p. 80).
This 3-acetylthio-2-methylpropanoic acid chloride (5.4 g.) and 2N sodium hydroxide (15 ml.) are added to a solution of L-proline (3.45 g.) in normal sodium hydroxide (30 ml.) chilled in an ice water bath. After 3 hours stirring at room temperature, the mixture is extracted with ether, the aqueous phase is acidified and extracted with ethyl acetate.
The organic phase is dried over magnesium sulfate and con-centrated to dryness to obtain l-(3-acetylthio-2-DL-methyl-propanoyl-L-proline).
Procedure C
Methacryloyl chloride (4.16 g.) is added to a solu-tion of L-proline (3.45 g.) in a mixture of water (100 ml.) and sodium bicarbonate (12 g.) chilled in an ice water bath, with vigorous stirring. When the addition is com-pleted, the mixture is stirred at room temperature for two hours, and then extracted with ether. The aqueous phase is acidified with N hydrochloric acid and extracted with ethyl acetate. The organic phase is concentrated to dry-ness in vacuo, the residue is mixed with thiolacetic acid (3.5 g.), a few crystals of azobisisobutyronitrile are added and the mixture is heated on the steam bath for two hours. The reaction mixture is dissolved in benzene-ace-tic acid (75:25), and applied to a column of silica gel.Elution with the same solvent mixture yields the 1-(3-ace-tylthio-2-DL-methylpropanoyl)-L-proline.
: .
~ $~
Example 30 1-(3-Benzoylthio-2-methylpropanoyl)-L-proline tert-butyl Ester By substituting 3-benzoylthio-2-methylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the procedure of Example 28, 1-(3-benzoylthio-2-methylpropanoyl)-L-proline tert.butyl ester is obtained.
Example 31 _ 1-(3-Phenylacetylthio-2-methylpropanoyl~-L-Proline tert-butvl Ester ~.
By substituting 3-phenylacetylthio-2-methylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the procedure of Example 28, 1-(3-phenylacetylthio-2-methyl-propanoyl)-L-proline tert butyl ester is obtained.
Example 32 1-(3-Benzoylthio-2-methylpropanoyl)-L-proline By substituting 1-(3-benzoylthio-2-methylpropanoyl)-L-proline tert-butyl ester for the 1-(3-acetylthio)-2-methylpropanoyl-l-proline tert-butyl ester in Procedure A
of Example 29, 1-(3-benzoylthio-2-methylpropanoyl)-L-pro-line is obtained.
Example 33 1-(3-Phenylacetylthio-2-methylpropanoyl)-L-proline By substituting 1-(3-phenylacetylthio-2-methylpro-panoyl)-L-proline tert-butyl ester for 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl es-ter in Procedure A of Example 29, 1-(3-phenylacetylthio-2-methylpropanoyl)-L-proline is obtained.
Example 34 1-(3-Mercapto-2-D-methylpropanoyl)-L-proline 1-(3-Mercapto-2-methylpropanoyl)-L-proline is ob-tained by treating the product of each of Examples 29, 32 and 33 as follows:
v~
The thioester (0.85 g.) is dissolved in 5.5 N ~etha-nolic ammonia and the solution is kept at room temperature for 2 hours. The solvent is removed in vacuo and the re-sidue is dissolved in water, applied to a ion exchange co-lumn on the H cycle (Dowex 50, analytical grade) and eluted with water. The fractions that give positive thiol reaction are pooled and freeze dried. The residue is cry-stallized from ethyl acetate-hexane, yield 0.3 g. The 1-(3-mercapto-2-D-methylpropanoyl-L-proline has m.p. 103-104, ~]D -131 (C,2,EtOH).
Example 35 1-(3-Acetylthio-2-methylpropanoyl)-L-Proline Methyl Ester 1-(3-Acetylthio-2-methylpropanoyl)-L-proline is re-acted witA an ethereal solution of diazomethane according to tAe procedure described in Example 3 to obtain 1-(3-acetylthio-2-methylpropanoyl)-L-proline methyl ester.
Example 36 1-~3-Mercapto-2-methylpropanoyl)-L-Proline amide By substituting 1-(3-acetylthio-2-methylpropanoyl)-L-proline methyl ester in the procedure of Example 4/ 1-(3-mercapto-2-methylpropanoyl)-L-proline amide is obtained.
Example 37 3-AcetyltAio-2-Benzylpropanoic Acid By substitutin~ 2-benzylacrylic acid for the metha-crylie aeid in the proeedure of Example 25, 3-acetylthio-2-benzylpropanoie aeid is obtained.
Example 38 1-(3-Aeetylthio-2-benzylpropanoyl)-L-Proline tert-butyl Ester By substitu~ing 3-aeetylthio-2-benzylpropanoie aeid for the 3-aeetylthio-2-methylpropanoie aeid in the proee-dure of :
.
"~j~, }~1 3r)b E~ample 22, 1-~3-acetylthio-2-benzylprop~noyl)-L-p~oline tert-butyl ester is obtained.
_xample 39__ _ 1-(3-Acetylthio-2-benzylpropanoyl)-L-Proline ~ _ _ _ _ _ The product of Example 38 is substituted for the 1-(3-acetylthio-2-methylpropanoyl-L-proline tert-butyl ester in the Procedure A of Example 29 to obtain 1-(3-acetylthio-2-benzylpropanoyl)-L-proline.
Example 40 1-~3-Mercapto-2-benzylpropanoyl)-L-Proline 1-(3-Acetylthio-2-benzylpropanoyl)-L-proline is treated with methanolic ammonia according to the procedure oE Example 34 to obtain 1-(3-mercapto-2-benzylpropanoyl)-L-proline as an oil, R~ = 0.47 (silica gel, benzene-acetic acid (75:25).
Example 41 1-(3-Mercapto-2-methylpropanoyl)-L-Hydroxy Proline By substituting L-hydroxy proline tert-butyl ester in the procedure of Example 28, treating the product according to Procedure A of Example 29 and then continuing as in Example 34, 1-(3-acetylthio-2-methylpropanoyl)-L-hydroxyproline tert-butyl ester, l-(3-acetylthio-2-methylpropanoyl)-L-hydroxyproline and l-~3-mercapto-2-methylpropanoyl)-L-hydroxyproline, respectively, are obtained.
Example 42 1-(3-Mercapto-2-methylpropanoyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid tert-butyl ester in the procedure of Example 28, treating the product according to the Procedure A of Example 29 and then continuing as -in Example 3~ (3-acetylthio-2-methylpropanoyl)-L-azetidine-2-carboxylic acid tert-butyl es-ter, 1,3-acetylthio-2-methyl-propanoyl)-L-azetidine-2-carboxylic acid ancl 1-(3-mercapto-2-methylpropanoyl-L-azetidine-2-carboxylic acid are obtained.
_ample ~3 1-(3-1~lercapto-2-methylpropanoly)-L-Pipecolic Acid By substituting L-pipecolic acid in the procedure of Example 28, treating the product according to Procedure A of Example 29 and then continuing as in Example 34, 1-(3-acetyl-thio-2-methylpropanoyl)-L-pipecolic acid tert-butyl ester, 1-(3-acetylthio-2-methylpropanoyl)-L-pipecolic acid and 1-(3-mercapto-2-methylpropanoyl)-L-pipecolic acid, respectively, are obtained.
Example 44 1-(4-Benzoylthiobutanoyl)-L-Proline To a solution of L-proline (2.88 g.) in normal sodium hydroxide (25 ml.) chilled in an ice bath, 2N sodium hydroxide (12.5 ml.) and 4-chlorobutyryl chloride (3.5 g.) are added.
The reaction mixture is stirred at room temperature for 3.5 hours and a suspension of thiobenzoic acid (3.75 g.) and potassium carbonate (2.4 g.) in water (25 ml.) is added. After overnight stirring at room temperature, the reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is dried over magnesium sul-fate and concentrated to dryness in vacuo. The residue is chromatographed on a column of silica gel with benzene-acetic acid (7:1). The fractions containing the desired material are pooled and concentrated to dryness, yield 1.35 g. A small aliquot of this material is dissolved in ethyl acetate and dicyclohexylamine is added until pH 8-10 (on a wet pH paper).
,. . .
3.~5 ~3 The dicyclohe~ylamine salt crystallizes out, immediately, m.p.
159-161.
Example 45 . . _ 1-(4-Mercaptobutanoyl ? -L-Proline 1-(4-Benzylthiobutanoyl)-L-proline (1.08 g.) is dissolved in a mixture of water (4 ml.) and concentra-ted ammonia (2.7 ml.). After one hour stirring at room tempera-ture, the mixture is diluted with water, filtered, extracted with ethyl acetate, and the aqueous phase was concentrated in vacuo.
This ammonium salt of 1-(4-mercaptobutanoyl)-L-proline is purified by ion exchange chromatography on a column of diethyl-aminoethyl-Sephadex (cross linked dextran) with a gradient of ammonium bicarbonate, yield 0.7 g. The ammonium salt is dissolved in water (2 ml.) and applied to a column of Dowex 50 sulfonic acid resin analytical grade in the hydrogen form, ana the free acid is eluted with water. The fractions containing the desired material (sulfhydryl reagent and carboxyl reagent positive) are pooled and freeze dried to obtain 1-(4-mercaptobutanoyl)-L-proline. The dicyclohexyl ammonium salt is produced by the procedure of Example 44, m.p. 157-158.
Example 46
Example 26 3-Benzoylthio-2-Methylpropanoic Acid By substituting thiobenzoic acid for the thioace-tic acid in the procedure of Example 25, 3-benzoylthio-2-methylpropanoic acid is obtained.
Example 27 3-Phenylacetylthio-2-Methylpropanoic Acid By substituting thiophenylacetic acid for the thio-acetic acid in the procedure of Example 25, 3-phenylacetyl thio-2-methylpropanoic acid is obtained.
Example 28 1-(3-Ace-tylthio-2-methylpropanoyl)-L-Proline tert-butyl Ester L-Proline tert-butyl ester (5.1 g.) is dissolved in dichloromethane (40 ml.) and the solution stirred and chilled ~ ~ -29-.
in an ice bath. Dicyclohexylcarbodiimide (6.2 g.) dissolved in dichloromethane (15 ml.) is added followed immediately by a solution of 3-acetylthio-2-methylpropanoic acid (4.9 g.) in dichloromethane (5 ml.). A~ter 15 minutes stirring in the ice bath and 16 hours at room temperature, the precipi-tate is filtered off and the filtrate is concentrated to !
dryness in vacuo. The residue is dissolved in ethyl acet-ate and washed neutral. The organic phase is dried over magnesium sulfate and concentrated to dryness in vacuo.
The residue 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester is purified by column chromatography (silica gel-chloroform), yield 7.9 g.
Example 29 1-(3-Acetylthio-2-methylpropanoyl)-L-Proline Procedure A
The 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester of Example 28 (7.8 g.) is dissolved in a mixture of anisole (55 ml.) and trifluoroacetic acid (110 ml.). After one hour storage at room temperature the sol-vent is removed in vacuo and the residue is precipitatedseveral times from ether-hexane. The residue (6.8 g.) is dissolved in acetonitrile (40 ml.) and dicyclohexylamine (4.5 ml.) is added. The crystalline salt is boiled with fresh ~cetonitrile (100 ml.), chilled to room temperature and filtered, yield 3.8 g., m.p. (165) 187-188. This ma-terial is recrystallized from isopropanol [~]D-67 (C 1.4, EtOH). The crystalline dicyclohexylamine salt is suspen-ded in a mixture of 5% aqueous potassium bisulfate and ethyl acetate. The organic phase is washed with water and concentrated to dryness. The residue is crystallized from ethyl acetate-hexane to`yield the l-(3-acetyl-5~
thio-~-D-methylpropanoyl-L-proline, m.p. 83-85[~]D -162 ( c , 1 . 7 , E tO~).
Procedure B
3-Acetylthio-2-methylpropanoic acid (8.1 g.) and thio-nyl chloride ( 7 g . ) are mixed and the suspension is stirred for 16 hours at room temperature. The reaction mixture is concentrated to dryness and distilled in vacuo ~b.p. 80).
This 3-acetylthio-2-methylpropanoic acid chloride (5.4 g.) and 2N sodium hydroxide (15 ml.) are added to a solution of L-proline (3.45 g.) in normal sodium hydroxide (30 ml.) chilled in an ice water bath. After 3 hours stirring at room temperature, the mixture is extracted with ether, the aqueous phase is acidified and extracted with ethyl acetate.
The organic phase is dried over magnesium sulfate and con-centrated to dryness to obtain l-(3-acetylthio-2-DL-methyl-propanoyl-L-proline).
Procedure C
Methacryloyl chloride (4.16 g.) is added to a solu-tion of L-proline (3.45 g.) in a mixture of water (100 ml.) and sodium bicarbonate (12 g.) chilled in an ice water bath, with vigorous stirring. When the addition is com-pleted, the mixture is stirred at room temperature for two hours, and then extracted with ether. The aqueous phase is acidified with N hydrochloric acid and extracted with ethyl acetate. The organic phase is concentrated to dry-ness in vacuo, the residue is mixed with thiolacetic acid (3.5 g.), a few crystals of azobisisobutyronitrile are added and the mixture is heated on the steam bath for two hours. The reaction mixture is dissolved in benzene-ace-tic acid (75:25), and applied to a column of silica gel.Elution with the same solvent mixture yields the 1-(3-ace-tylthio-2-DL-methylpropanoyl)-L-proline.
: .
~ $~
Example 30 1-(3-Benzoylthio-2-methylpropanoyl)-L-proline tert-butyl Ester By substituting 3-benzoylthio-2-methylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the procedure of Example 28, 1-(3-benzoylthio-2-methylpropanoyl)-L-proline tert.butyl ester is obtained.
Example 31 _ 1-(3-Phenylacetylthio-2-methylpropanoyl~-L-Proline tert-butvl Ester ~.
By substituting 3-phenylacetylthio-2-methylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the procedure of Example 28, 1-(3-phenylacetylthio-2-methyl-propanoyl)-L-proline tert butyl ester is obtained.
Example 32 1-(3-Benzoylthio-2-methylpropanoyl)-L-proline By substituting 1-(3-benzoylthio-2-methylpropanoyl)-L-proline tert-butyl ester for the 1-(3-acetylthio)-2-methylpropanoyl-l-proline tert-butyl ester in Procedure A
of Example 29, 1-(3-benzoylthio-2-methylpropanoyl)-L-pro-line is obtained.
Example 33 1-(3-Phenylacetylthio-2-methylpropanoyl)-L-proline By substituting 1-(3-phenylacetylthio-2-methylpro-panoyl)-L-proline tert-butyl ester for 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl es-ter in Procedure A of Example 29, 1-(3-phenylacetylthio-2-methylpropanoyl)-L-proline is obtained.
Example 34 1-(3-Mercapto-2-D-methylpropanoyl)-L-proline 1-(3-Mercapto-2-methylpropanoyl)-L-proline is ob-tained by treating the product of each of Examples 29, 32 and 33 as follows:
v~
The thioester (0.85 g.) is dissolved in 5.5 N ~etha-nolic ammonia and the solution is kept at room temperature for 2 hours. The solvent is removed in vacuo and the re-sidue is dissolved in water, applied to a ion exchange co-lumn on the H cycle (Dowex 50, analytical grade) and eluted with water. The fractions that give positive thiol reaction are pooled and freeze dried. The residue is cry-stallized from ethyl acetate-hexane, yield 0.3 g. The 1-(3-mercapto-2-D-methylpropanoyl-L-proline has m.p. 103-104, ~]D -131 (C,2,EtOH).
Example 35 1-(3-Acetylthio-2-methylpropanoyl)-L-Proline Methyl Ester 1-(3-Acetylthio-2-methylpropanoyl)-L-proline is re-acted witA an ethereal solution of diazomethane according to tAe procedure described in Example 3 to obtain 1-(3-acetylthio-2-methylpropanoyl)-L-proline methyl ester.
Example 36 1-~3-Mercapto-2-methylpropanoyl)-L-Proline amide By substituting 1-(3-acetylthio-2-methylpropanoyl)-L-proline methyl ester in the procedure of Example 4/ 1-(3-mercapto-2-methylpropanoyl)-L-proline amide is obtained.
Example 37 3-AcetyltAio-2-Benzylpropanoic Acid By substitutin~ 2-benzylacrylic acid for the metha-crylie aeid in the proeedure of Example 25, 3-acetylthio-2-benzylpropanoie aeid is obtained.
Example 38 1-(3-Aeetylthio-2-benzylpropanoyl)-L-Proline tert-butyl Ester By substitu~ing 3-aeetylthio-2-benzylpropanoie aeid for the 3-aeetylthio-2-methylpropanoie aeid in the proee-dure of :
.
"~j~, }~1 3r)b E~ample 22, 1-~3-acetylthio-2-benzylprop~noyl)-L-p~oline tert-butyl ester is obtained.
_xample 39__ _ 1-(3-Acetylthio-2-benzylpropanoyl)-L-Proline ~ _ _ _ _ _ The product of Example 38 is substituted for the 1-(3-acetylthio-2-methylpropanoyl-L-proline tert-butyl ester in the Procedure A of Example 29 to obtain 1-(3-acetylthio-2-benzylpropanoyl)-L-proline.
Example 40 1-~3-Mercapto-2-benzylpropanoyl)-L-Proline 1-(3-Acetylthio-2-benzylpropanoyl)-L-proline is treated with methanolic ammonia according to the procedure oE Example 34 to obtain 1-(3-mercapto-2-benzylpropanoyl)-L-proline as an oil, R~ = 0.47 (silica gel, benzene-acetic acid (75:25).
Example 41 1-(3-Mercapto-2-methylpropanoyl)-L-Hydroxy Proline By substituting L-hydroxy proline tert-butyl ester in the procedure of Example 28, treating the product according to Procedure A of Example 29 and then continuing as in Example 34, 1-(3-acetylthio-2-methylpropanoyl)-L-hydroxyproline tert-butyl ester, l-(3-acetylthio-2-methylpropanoyl)-L-hydroxyproline and l-~3-mercapto-2-methylpropanoyl)-L-hydroxyproline, respectively, are obtained.
Example 42 1-(3-Mercapto-2-methylpropanoyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid tert-butyl ester in the procedure of Example 28, treating the product according to the Procedure A of Example 29 and then continuing as -in Example 3~ (3-acetylthio-2-methylpropanoyl)-L-azetidine-2-carboxylic acid tert-butyl es-ter, 1,3-acetylthio-2-methyl-propanoyl)-L-azetidine-2-carboxylic acid ancl 1-(3-mercapto-2-methylpropanoyl-L-azetidine-2-carboxylic acid are obtained.
_ample ~3 1-(3-1~lercapto-2-methylpropanoly)-L-Pipecolic Acid By substituting L-pipecolic acid in the procedure of Example 28, treating the product according to Procedure A of Example 29 and then continuing as in Example 34, 1-(3-acetyl-thio-2-methylpropanoyl)-L-pipecolic acid tert-butyl ester, 1-(3-acetylthio-2-methylpropanoyl)-L-pipecolic acid and 1-(3-mercapto-2-methylpropanoyl)-L-pipecolic acid, respectively, are obtained.
Example 44 1-(4-Benzoylthiobutanoyl)-L-Proline To a solution of L-proline (2.88 g.) in normal sodium hydroxide (25 ml.) chilled in an ice bath, 2N sodium hydroxide (12.5 ml.) and 4-chlorobutyryl chloride (3.5 g.) are added.
The reaction mixture is stirred at room temperature for 3.5 hours and a suspension of thiobenzoic acid (3.75 g.) and potassium carbonate (2.4 g.) in water (25 ml.) is added. After overnight stirring at room temperature, the reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is dried over magnesium sul-fate and concentrated to dryness in vacuo. The residue is chromatographed on a column of silica gel with benzene-acetic acid (7:1). The fractions containing the desired material are pooled and concentrated to dryness, yield 1.35 g. A small aliquot of this material is dissolved in ethyl acetate and dicyclohexylamine is added until pH 8-10 (on a wet pH paper).
,. . .
3.~5 ~3 The dicyclohe~ylamine salt crystallizes out, immediately, m.p.
159-161.
Example 45 . . _ 1-(4-Mercaptobutanoyl ? -L-Proline 1-(4-Benzylthiobutanoyl)-L-proline (1.08 g.) is dissolved in a mixture of water (4 ml.) and concentra-ted ammonia (2.7 ml.). After one hour stirring at room tempera-ture, the mixture is diluted with water, filtered, extracted with ethyl acetate, and the aqueous phase was concentrated in vacuo.
This ammonium salt of 1-(4-mercaptobutanoyl)-L-proline is purified by ion exchange chromatography on a column of diethyl-aminoethyl-Sephadex (cross linked dextran) with a gradient of ammonium bicarbonate, yield 0.7 g. The ammonium salt is dissolved in water (2 ml.) and applied to a column of Dowex 50 sulfonic acid resin analytical grade in the hydrogen form, ana the free acid is eluted with water. The fractions containing the desired material (sulfhydryl reagent and carboxyl reagent positive) are pooled and freeze dried to obtain 1-(4-mercaptobutanoyl)-L-proline. The dicyclohexyl ammonium salt is produced by the procedure of Example 44, m.p. 157-158.
Example 46
4-Bromo-2-Methylbutanoic Acid Ethyl-4-bromo-2-methylbutanoate [G. Jones and J. Wood, Tetrahedron, 21, 2961 (1965)] (1.04 g.) is dissolved in dichloromethane (50 ml.) and cooled to -10. A 1 M solution of boron tribromide in dichloromethane ~50 ml.) is added dropwise with stirr:ing and the stirring is continued for 1 hour at -10 and 2 hours at 25. The reaction is terminated , by the careful addition of ~ater. The layers are separated and the organic phase is washed with wa-ter, dried and concen~
trated to dryness to obtain 4-bromo-2-methylbutanoic acid.
Example 47 1-(4-Benzoylthio-2-methylbutanoyl)-l-Proline a) 4-sromo-2-methylbutanoic acid (8 g.) and thionyl chloride (7 g.) are mixed and the mixture is stirred for 16 hours at room temperature. The reaction mixture is concentrated to dryness and distilled in vacuo.
b) To a solution of L-proline (2.88 g.) in normal sodium hydroxide (25 ml.) chilled in an ice bath, 2N sodium hydroxide (12.5 ml.) and the 4-bromo-2-methylbutanoic acid chloride ob,ained in part (a) (3.9 g.) are added. The reaction mixture is stirred at room temperature for 3.5 hours and a suspension of thiobenzoic acid (3.75 g.) and potassium carbonate (2.4 g.) in water (25 ml.) is added. After overnight stirring at room temperature, the reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue is chromatographed on a column of silica gel with benzene-acetic acid (7:1). The fractions containing the desired product, 1-(4-benzoylthio-2-methylbutanoyl)-L-proline are pooled and concentrated to dryness in vacuo.
Example 48 1-(4-Mercapto-2-methylbutanoyl)-L-Proline _ By substitu1ting 1-(4-benzoylthio-2-methylbutanoyl)-L-proline for the L-(4-benzoylthiobutanoyl)-L-proline in the procedure of Example 45, 1-(mercapto-2-methylbutanoyl)-L-proline in obtained.
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s~
Example 49 4-sromo-2-benzylbutanoic acid By substituting ethyl-4-bromo-2-benzylbutanoate [prepared by the procedure of G. Jones and J. Wood lTetrahedron, 21, 2961 (1965) starting with diethylbenzylmalonate]] for the ethyl-4-bromo-2-methylbutanoate in the procedure of Example 46, 4-bromo-2-benzylbutanoic acid is obtained.
Example 50 1-(4-Benzoylthio-2-benzylbutanoyl)-L-Proline By substituting 4-bromo-2-benzylbutanoic acid for the 4-bromo-2-methylbutanoic acid in the procedure of Example 47, 1-(4-benzoylthio-2-benzylbutanoyl)-L-proline is obtained.
Example 51 1-(4-Mercapto-2-benzylbutanoyl)-L-Proline By substituting 1-(4-benzoylthio-2-benzylbutanoyl)-L-proline for the l-(4-benzoylthiobutanoyl)-L-proline in the procedura of Example 45, 1-(mercapto-2-benzylbutanoyl)-L-proline is obtained.
Example 52 1-(4-Mercaptobutanoyl)-L-Hydroxyproline By substituting L-hydroxyproline for the L-proline in the procedure of Example 44 and subjecting the product to ammonolysis as in Example 45, 1-(4-benæoylthiobutanoyl)-L-hydroxy-proline and l-(4-mercaptobutanoyl)-L-hydroxyproline, respectively, are obtained.
Example 53 1-(4-Mercaptobutanoyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid for the L-proline in the procedure of Example 44 and subjecting the product to ammonolysis as in Example 45, l--(4-benzoylthio-butanoyl)-L-azetidine-2-carbo~ylic acid and l-(4-mercapto-butanoyl)-L-azetidine-2-carboxylic acid, respectively, are obtained.
Example 54 1-(4-Mercaptobutanoyl)-L-Pipecolic Acid _ _ By substituting L-pipecolic acid for the L-proline in the procedure of Example 44 and subjecting the product to ammonolysis as in Example 45, l-(4-benzoylthiobutanoyl)-L-pipecolic acid and 1-(4-mercaptobutanoyl)-L-pipecolic acid, respectively, are obtained.
Example 55 l-(3-Acetylthiobutanoyl)-L-Proline tert-butyl Ester Dicyclohexylcarbodiimide (6.2 g.) and 3-acetylthio-butyric acid (4.86 g.) are added to a solution of L-proline tert-butyl ester (5.1 g.) in dichloromethane (60 ml.) stirred in an ice bath. After 15 minutes the ice bath is removed and the mixture is stirred at room temperature for 16 hours.
The precipitate is filtered, the filtrate is concentrated to dryness and the residue is chromatographed on a column of silica gel with chloroform to obtain 1-(3-acetylthiobutanoyl)-L-proline tert-butyl ester, yield 5.2 g.
Example 56 1-~3-Acetylthiobutanoyl)-L-Proline _ .
The 1-(3-acetylthiobutanoyl)-L-proline tert-butyl ester of Example 55 (5.2 g.) is dissolved in a mixture of trifluoro-acetic acid (60 ml.) and anisole (30 ml.) and the solution is kept at room temperature for one hour. The solvents are removed in vacuo and the residual l-(3-acetylthiobutanoyl)-L-proline is reprecipitated from ether-hexane several times, yield .
4 g.. The dicyclohexylamine salt is made by the procedure of Example ~4, m.p. 175-176.
Example 57 1-(3-Mercaptobutanoyl)-L-Proline The 1-(3-acetylthiobutanoyl)--L-proline of Example 56 (0.86 g.) is dissolved in 5.5 N. methanolic ammonia (20 ml.) and the reaction mixture is stored at room temperature for 2 hours. The solvent is removed in vacuo and the residue chromatographed on an ion exchange column (Dowex 50) with water. The fractions containing the desired 1-(3-mercaptobutanoyl)-L-proline are pooled and lyophilized, yield 0.6 g. The dicyclohexylamine salt is produced by the procedure of Example 44, m.p. 183-184.
Example 58 1-[3-[[(Ethoxy)carbonyl]thio]propanoyl]-L-proline Ethyl chloroformate (1.2 g.) is added to a solution of 3-mercaptopropanoyl-L-proline (2.03 g.) in normal sodium bicar-bonate (30 ml.) and the mixture is stirred vigorously at 5 ~or one hour, and for two hours at room temperature. ~fter acidification with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. The organic phase is washed with water, dried over magnesium sulfate, and concentra-ted to dryness to yield l-[3-[[(ethoxy)carbonyl]thio]propanoyl]-L-proline.
.~ .
~ ~W3.~
Example 59 1-[3-[[(Ethoxy)thiocarbonyl]thio]propanoyl]-L-proline Aqueous 2N sodium hydroxide ~25 ml) and 3-bromopropionyl chloride (8.5 g) are added to a solution of L-proline (5.75 g) in N sodium hydroxide (50 ml) chilled and stirred in an ice bath. After five minutes the ice bath is removed and the stirring is continued at room temperature. After three hours ethyl xantogenic acid potassium salt (9.6 g) is added and the mixture is stirred overnight at room temperature. The solution is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is concentrated to dry-ness and the residue is chromatographed on a column of silica gel with a mixture of benzene-acetic acid (7:1) as solvent, to yield 1-[3-[[(ethoxy)thiocarbonyl]thio]propanoyl]-L-proline, m.p. 94-95.
Example 60 1-[3-[[(Benzylthio)carbonyl]thio]propanoyl]-L-proline A solution of benzylthiocarbonyl chloride (11 ml) in dioxane (20 ml) is added in five portions to a solution of 1-(3-mercaptopropanoyl)-L-proline (1.6 g) in normal sodium bicarbonate (24 ml) chilled in an ice bath, over a period of 30 minutes. The ice bath is removed and the stirring is continued for 2.5 hours at room temperature. After acid-ification with concentrated hydrochloric acid, the aqueous phase is extracted with eth~l acetate. The organic phase is dried over magnesium sulfate and concentrated to dryness to yield 1-[3-[~(benzylthio)carbonyl]thio]propanoyl]-L-proline.
, `''~ 1, ;` : , Example 61 1-[3-[[(Ethylthio)thiocarbonyl]thio]propanoyl]-l-proline Aqueous 2N sodium hydroxide (25 ml) and 3-bromopropionyl chloride (8.5 g) are added to a solution of L-proline (5.75 g) in N sodium hydroxide (50 ml) chilled and stirred in an ice bath. After five minutes, the ice bath is removed and the stirring is continued at room temperature. After three hours, ethyl trithiocarbonate potassium salt (10.5 g) is added and the mixture is stirred at room temperature overnight. After aeidification with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and concentrated to dryness to yield 1-~3-[[(ethylthio~hioearbonyl]thio]propanoyl]-~-proline.
Example 62 3-[[(Methylamino)thiocarbonyl]thio]propionic acid Methylisothiocyanate (4 g) is added to a solution of 3-mereaptopropionie aeid (5.3 g) in a mixture of pyridine (250 ml) and 0.5 N sodium hydroxide (100 ml). The solution is kept at 40 for two hours and eoneentrated to dryness in vacuo. The residue is dissolved in water (100 ml.), aeidified with concentrated hydrochloric acid and extraeted with ether. The organie phase is concentrated to dryness to yield 3-[[(methylamino)thiocarbonyl]thio]propionic acid, m.p. 86-87.
~i :
3,`~
E~ample 63 _ 1-[3-[[(Methylamino)thiocarbonyl]thio]pr~ yl~
tert-butyl ester To a solution of L-proline tert-butyl ester (1.71 g) and hydroxybenzotriazole (1.35 g) in dichloromethane (10 ml) chilled and stirred in an ice bath, dicyclohexylcarbodiimide (2.06 g) and 3-methylaminothiocarbonylthiopropionic acid (1.79 g) are added. After 15 minutes, the bath is removed and the stirring is continued overnight. The precipitate is filtered off and the filtrate is diluted with ethyl acetate and washed neutral.
The organic phase is concentrated to dryness to yield 1-~3-t[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline tert-butyl ester, m.p. 129-130.
Example 64 1-13-[[(Methylamino)thiocarbonyl]thio]propanoyl]-L-proline A) l-(Methylaminothiocarbonylthiopropanoyl)-L-proline tert-butyl ester (0.98 g) is dissolved in a mixture of anisole (3.6 ml) and trifluoroacetic acid (7.5 ml). After one hour at room temperature the mixture is concentrated to dryness in vacuo and the residue precipitated from ether-hexane three times. This material is chromatographed on a column of silica gel with a solvent mixture of benzene-acetic acid (75:25) to yield 1-[3-[[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline, Rf = 0.4 [silica gel-benzene:acetic acid (75:25)]. The , dicyclohexylammonium salt has m.p. 127-129.
;, I
s) ~lethylisothiocyanate (4 g) is added to a solution of 3-mercaptopropanoyl-L-proline (10.1 g) in a mixture of pyridine (250 ml) and 0.5 N sodium hydroxide (100 ml). The solution is kept at 40 for two hours and concentrated to dryness ln vacuo.
The residue is dissolved in water (100 ml), acidified with con-centrated hydrochloric acid and extracted with ethyl acetate.
The organic phase is concentrated to dryness to yield 1-[3-[[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline.
Example 65 1-[3-r[(Ethylamino)carbonyl]thio]propanoyl]-L-proline Ethylisocyanate ~0.45 ml) is added to a solution of 1-(3-mercaptopropanoyl)-L-proline (1 g) in a mixture of N
sodium hydroxide (5 ml) and pyridine (5 ml). The solution is heated at 40 for four hours and concentrated in vacuo.
The residue is distributed between 0.1 N hydrochloric acid and ethyl acetate. The organic layer is washed with water, dried over magnesium sulfate and concentrated to dryness to yield l-[3-[[(ethylamino)carbonyl]thio]propanoyl]-L-proline.
The dicyclohexylammonium salt is prepared by adding dicyclo-hexylamine to a solution of the free acid in ethyl acetate,m.p. 150-152.
Example 66 .
1-[3-[1(Ethoxy)carbonyl]thio]-2-methylpropanoyl]-L-proline By substituting 1-(3-mercapto-2-methylpropanoyl]-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 58, 1-[3-[[(ethoxy)carbonyl]thio]-2-methylpropanoyl]-L-proline is obtainecl.
-4~-s~
xample 67 1-[3-[l(Ethoxy)carbonyl]_hio]butanoyl~-L-proline By substituting 1-(3-mercaptobutanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 58, 1-[3-[[(ethoxy)carbonyl]thio]butanoyl]-L~pro-line is obtained.
Example 68 1-[3-[l(Ethoxy)thiocarbonyl]thio~propanoyl]-L-azetidine-2-carboxylic acid By substituting L-azetidine-2-carboxylic acid for L-proline in the procedure of Example 59, 1-[3-[l(ethoxy)-thiocarbonyl]thio]propanoyl]-L-azetidine-2-carboxylic acid is obtained.
Example 69 1-13-11(Ethoxy)thiocarbonyl]thio]propanoyl]-L-pipecolic acid By substituting L-pipecolic acid for L-proline in the procedure of Example 59, 1-[3-[[(ethoxy)thiocarbonyl]-thio]propanoyl]-L-pipecolic acid is obtained.
Example 70 1-14-[[(Benzylthio)carbonyl]thio]butanoyl]-L-proline By substituting 4-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 60, 1-[4-[l(benzylthio)carbonyl]thio]butanoyl]-L-proline is obtained.
Example 71 1-[2-[[(Benzylthio)carbonyl]thio]propanoyl~-L-proline By substituting 2-mercaptopropanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 60, 1-[2-[[(benzylthio)carbonyl]thio]propanoyl]-L-proline is obtained.
~ .' .
Example 72 1-[3-[[(Ethylthio)thiocarbonyl]-thio~propanoyl]-L-proline methyl . .
ester A solution of 1-[3-[[(e-thylthio)thiocarbonyl]thio]-propanoyl]-L-proline in ethyl acetat.e is treated with an ethereal solution of diazomethane until persi.stent yellow color. Af-ter discharging the yellow color with a few drops of acetic acid, the solvents are removed in vacuo to yield l-[3-[[(ethylthio)-thiocarbonyl]thio]propanoyl]-L-proline methyl ester.
Example 73 1-[3-[[(methylamino)thiocarbonyl]thio]propanoyl]-5-hydroxy-L-pipecolic acid By substituting 1-(3-mercaptopropanoyl)-5-hydroxy-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the Procedure B of Example 64, 1-[3-[[(methylamino)thiocarbonyl]thio]-propanoyl]-5-hydroxy-L-pipecolic acid is obtained~ ¦
Example 74 l-t3-[[(Methylamino)thiocarbonyl]thio]-2-methylpropanoyl]-L-proline amide By substituting l-t3-mercapto-2-methylpropanoyl)-L-proline amide for the 3-mercaptopropanoyl-L-proline in the Procedure B of Exanple 64, 1-[3-[[(methylamino)thiocarbonyl]thio]- ' 2-methyl-propanoyl]-L-proline amide is obtained.
Example 75 1-[3-[[(Phenoxy)carbonyl]thi_]propanoyl]-L-proline By substituting phenylchloroformate for ethyl chloroformate in the procedure of Example 58, 1-[3-[[(phenoxy)carbonyl]thio]-propanoyl]-L-proline is obtained.
Example 76 1-[3-[[(Phenoxy)carbonyl]thio]butan_yl]-L-p oline By substituting phenylchloroformate for the e~hyl chloroformate and 4-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 58, 1-[3-~[(phenoxy)carbonyl]thio]butanoyl]-L-proline is obtained.
Example 77 1-[3-[[(Phenylamino)carbonyl]thio]propanoyl]-L-proline By substituting phenylisocyanate for the ethylisocyanate in the procedure of Example 65, 1-[3-[[(phenylamino)carbonyl]-thio]propanoyl]-L-proline is obtained.
Example 78 1-[3-[[(Phenethylamino)carbonyl]thio]propanoyl]-L-proline By substituting phenethylisocyanate for the ethylisocyanate in the procedure of Example 65, 1-[3-1[(phenethylamino)carbonyl]-thio]propanoyl]-L-proline is obtained.
Example 79 1-13-[~(Ethylamino)carbonyl]thio]-2-benzylpropanoyl]-L-proline By substituting 1-(3-mercapto-2-benzylpropanoyl)-L-proline for the l-(3-mercaptopropanoyl)-L-proline in the procedure of Example 65, 1-[3-[[(ethylamino)carbonyl]thio]-2-benzylpropanoyl]-L-proline is obtained.
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Example 80 1-(3-Methylthiopropanoyl ? -L-proline A) ~lethyl 3-methylthiopropionate (51 g) is saponi~ied with a lOQ sodium hydroxide solution (150 ml, 30 minutes at 100).
The cooled solution is extracted with ether and then acidified.
The crude acid thus obtained is distilled and converted to the acid chloride with thionyl chloride.
A solution of L-proline (11.5 g) in N sodium hydroxide (100 cc) is chilled in an ice bath and the 3-methylthiopropanoic acid chloride (6.9 g) is added dropwise with vigorous stirring over a ten minutes period. After five hours the reaction mixture is acidified and extracted with ethyl ether to yield 1-(3-methylthiopropanoyl)-L-proline. The dicyclohexylammonium salt is prepared by adding dicyclohexylamine to a solution of the free acid in ethyl acetate, m.p. 169-171.
~) Methyl iodide (71 g) is added to a solution of 1-(3-mercaptopropanoyl)-L-proline ethyl ester (115 g) and sodium (11.5 g) in ethanol (400 ml). The reaction is allowed to proceed overnight, the ethanol is removed in vacuo and the residue is dissolved in a mixture of ethyl acetate and water.
The organic layer is dried and concentrated to dryness in vacuo.
The resulting 1-(3-methylthiopropanoyl)-L-proline ethyl ester (98 g) is suspended in a mixture of methanol (200 ml) and 5 N
sodium hydroxide (200 ml) and stirred at room temperature for five hours. The methanol is removed in vacuo, and the aqueous phase is extracted with ethyl acetate, acidified and reextracted with ethyl acetate. This last organic phase is washed with water, dried and concentrated to dryness to yield l-(3-methylthio-prGpanoyl)-L-proline.
!
Example 81 1-[3-(4-Chlorophenylthio)propanoyl]-L-proline Aqueous 2 N sodium hydroxide (25 ml) and 3-bromopropionyl chloride (8.5 g) are added to a solution of L-proline (5.75 g) in N-sodium hydroxide (50 ml) chilled and stirred in an ice bath. After five minutes, the ice bath is removed and the stirring is continued for three hours at room temperature. The reaction mixture is acidified with concentrated hydrochloric acid ~nd extracted with ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness in vacuo. The residue is dissolved in a mixture of 4-chlorobenzenethiol (8 g), sodium hydroxide (4.2 g) and ethanol (300 ml). The solution is re~luxed for 6 hours. The solvent is removed in vacuo and the residue is dissolved in water, acidified with concentrated hydro-chloric acid and extracted with ethyl acetate. The organic layer is washed with water, dried, and concentrated to dryness in vacuo to yield l-[3-(4-chlorophenylthio)propanoyl]-L-proline.
Ex mple 82 ~ (3-Benzylthiomethyl)thio]propanoyl]-L-proline 1-(3-Mercaptopropanoyl)-L-proline (8.1 g) is dissolved in boiling liquid ammonia (100 ml) and small pieces of sodium are added until permanent blue color is obtained which is then discharged with a small piece of ammonium chloride. Benzyl-thiomethyl chloride (6.9 g) is added and the ammonia is allowed to evaporate. The final traces of ammonia are removed in vacuo, the residue is dissolved in water and extracted with ethyl acetate. The aqueous phase is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness ~Y
to yield 1-~[(3-benz~lthiomethyl)-thio]propanoyl]-L-proline.
Example 83 1-[[(3-Acetamidomethyl)thio]propanoyl]-L-proline 1-(3-Mercaptopropanoyl)-L-proline (2 g) and N-hydroxy-methylacetamide (0.89 g) are dissolved in trifluoroacetic acid (10 ml) and the solu-tion is stored at room temperature for one hour. The excess tirfluoroacetic acid is removed in vacuo and the residue is precipitated several times from ether-hexane.
Finally, the residue is distributed between dilute hydrochloric acid and ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness to yield l-[[3-acetamido-metnyl)thio]propanoyl]-L-proline.
Example 84 l-(~Iethylthioacetyl)-L-proline By substituting methyl methylthioacetate for the methyl 3-methylthiopropionate in the Procedure A of Example 80, 1-(methylthioacetyl)-L-proline, m.p. 123-124, is obtained.
` Example 85 l-(Benzylthioacetyl)-L-proline ~y substituting benzylthioacetyl chloride for the 3 methylthiopropanoyl chloride in the Procedure A of Example 80, l-(benzylthioacetyl)-L-proline, m.p. 86-88, is obtained.
, E~ample 86 1-[3-[(2-Pheny~ethyl)thio]propanoyl]-L-proline By substituting phenethylbromide for the methyl io-dide in the Procedure B of Example 80, 1-[3-[(2-phenyl-ethyl)thio]propanoyl]-L-proline is obtained.
Example 87 1-[3-[tTriphenylmethyl)thio]propanoyl]-L-proline By substituting triphenylmethyl chloride for the methyl iodide in the Procedure B of Example 80, 1-[3-[(triphenylmethyl)thio]propanoyl]-L-proline is obtained.
Example 88 1-(3-Methylthio-2-methylpropanoyl)-L-proline amide By substituting 1-(3-mercapto-2-methylpropanoyl)-L-proline amide for the l-(3-mercaptopropanoyl)-L-proline ethyl ester in the Procedure B of Example 80 and elimina-ting the saponification step, l-(3-methylthio-2-methylpro-panoyl)-L-proline amide is obtained.
Example 89 1-(3-Methylthiopropanoyl)-L-azetidine-2-carboxylic acid By substituting L-azetidine-2-carboxylic acid for the L-proline in the Procedure A of Example 80, 1-(3-methylthiopropanoyl)-L~azetidine-2-carboxylic acid is obtained.
,~ ~
. ~
E~ample 90 1-[3-(4-Me-thoxyphenylthio)propanoyl]-L-proline sy substituting 4-methoxybenzenethiol for the 4-chloro-benzenethiol in the procedure of Example 81, 1-[3-(4-methoxy-phenylthio)propanoyl]-L-proline is obtained.
Example 91 1-13-Methylthiopropanoyl)-L-pipecolic acid By substituting L-pipecolic acid for the L-proline in the Procedure A of Example 80, 1-(3-methylthiopropanoyl)-L-pipecolic acid is obtained.
Example 92 1-[2-(4-Chlorophenylthio propanoyl]-L-proline By substituting 2-bromopropionyl chloride for the 3-bromopropionyl chloride in the procedure of Example 81, 1-[2-(4-chlorophenylthio-propanoyl]-L-proline is obtained.
Example`93 1-13-[(Diphenylmethyl)thio]-2-benzylpropanoyl)]-L-proline Diphenylmethanol (0.92 g) and 1-(3-mercapto-2-benzyl-propanoyl)-L-proline (1.5 g) are dissolved in trifluoroacetic acid (10 ml) and the solution-is kept at room temperature for 30 minutes. The excess trifluoroacetic acid is removed in vacuo to yield l-[3-[~diphenylmethyl)thio]-2-benzylpropanoyl]-L-proline.
.
Example 94 _ 1-[4-(4-Chlorophenylthio)butanoyl]-L-proiine sy substituting 4-bromopropionyl chloride for the 3-bromopropionyl chloride in the procedure of Example 81, 1-[4-(4-chlorophenylthio)butanoyl]-L-proline is obtained.
Example 95 1-[3-[(Benzylthiomethyl)thio]butanoyl]-L-proline By substituting 3-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 82, 1-13-[(benzylthiomethyl)thio]butanoyl]-L-proline is obtained.
Example 96 l-E[4-[(Acetamidomethyl)thio]-2-methylbutanoyl]-L-proline sy substituting 1-(4-mercapto-2-methylbutanoyl)-L-proline for the 1-(3-mercaptopropanoyl)-L-proline in the procedure of Example 83, 1-[[4-~acetamidomethyl)thio~-2-methylbutanoyl]-L-proline is obtained.
Example 97 1-[3-(Ethyldithio)propanoyl]-L-proline A) 3-Mercaptopropanoyl-L-proline (10 g) is added to a solution of ethylthiosulfinate (8.4 g) in methanol (100 ml) and the reaction mixture is stirred vigorously at room temperature for four hours. The methanol is removed in vacuo to yield 1-(3-ethyldithiopropanoyl)-L-proline.
B) A solution of ethylthiosulfinate (8.4 g) in ethanol (50 ml) i9 added to an aqueous solution of 3-mercapto-propanoyl-L-proline (10 g) maintained at pH 6-7 by careful addition of sodium hydroxide. The mixture is stirred vigorously at room temperature until negative thiol reaction. The mix-ture is diluted with water, adjusted to pH 8 and extracted with ethyl acetate, the aqueous phase i5 acidified to pH 3 and extracted again with ethyl acetate. This latter extract is washed with water, dried and concentrated to dryness to yield l-[3-~ethyldithio)propanoyl]-L-proline.
Example 98 1-13-[(4-Methylphenyl)dithio]propanoyl]-L-proline A solution of 4-methylphenylsulfenyl chloride (1.76 g.) in ether (20 ml) is added to a solution of 3-mercaptopropanoyl-L-proline (2 g) in 0.5 N sodium hydroxide (20 ml) chilled in an ice bath. The mixture is stirred vigorously for one hour, and the aqueous phase is separated, acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic phase is washed with water, dried and concentrated to dryness to yield 1-[[3-(4-methylphenyl)dithio]propanoyl]-L-proline.
Example 99 1-[3-(Phenyldithio-propanoyl]-L-proline By substituting phenylthiosulfinate [prepared from phenyl-disulfide according to U. Weber and P. Hartter, Z. Physiol. Chem.,351, 1384 (1970)] for the ethylthiosulfinate in the procedure of Example 97, 1-[3-~phenyldithio-propanoyl]-L-proline is obtained.
Example 100 1-[3-[(2-Phenylethyl)dithio]propanoyl]-L-proline By substituting 2-phenylethylthiosulfinate (prepared from phenethyldisulfide) for the ethylthiosuflinate in the procedure of Example 97, 1-[3-[(2-phenylethyl)dithio]propanoyl]-L-proline is obtained.
Example 101 1-[3-[(2-Hydroxyethyl)dithio]propanoyl]-L-proline To a solution of 1,1'-[(sulfinylthio)-bis-(3-propanoyl)]-bis-L-proline (21 g) in methanol (100 ml), mercaptoethanol(4.2 g) is added and the reaction mixture is stirred vigorously at room temperature for four hours. The methanol is removed in vacuo and the residue is pruified by chromatography on a silica gel column to yield 1-[3-[(2-hydroxyethyl)dithio]propanoyl]-L-proline.
Example 102 1-12-(Ethyldithio)propanoyl]-L-proline By substituting 2-mercaptopropanoyl-L-proline for 3-mercaptopropanoyl-L-proline in the procedure of Example 97, 1-[2-(ethyldithio)propanoyl]-L-proline is obtained.
Example`103 1-13-~(4-Methylphenyl)dithio]butanoyl]-L-proline By substituting 3-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 98, 1-[3-(4-methylphenyl)dithio]butanoyl]-L-proline is obtained.
Example 104 1-13-(Ethyldithio)-2-methylpropanoyl]-L-proline methyl ester _ By substituting 1-(3-mercapto-2-methylpropanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 97 and then treating the product with ethereal diazomethane as in the procedure of Example 72, 1-[3-(ethyldithio)-2-methylpro-panoyl]-L-proline methyl ester is obtained.
~,~
Example 105 1-[3-(Ethyldithio)propanoyl]-L-azetidine-2-carbo~ylic acid By subs-ti-tuting 3-mercaptopropanoyl-L-azetidine-2-carboxylic acid Eor the 3-mercaptopropanoyl-L-proline ln the procedure of Example 97, 1-[3-(ethyldithio)propanoyl]-L-aze-tidine-2-carboxylic acid is obtained.
Example 106 1-[3-~(4-Methylphenyl)dithio]-2-methylpropanoyl]-L-hydroxyproline By substituting 1-(3-mercapto-2-methylpropanoyl)-L-hydroxy proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 98, 1-[(3-[4-methylphenyl)dithio]-2-methylpropanoyl]-L-hydroxyproline is obtained.
Example 107 1-[4-tEthyldithio)butanoyl]-L-pipecolic acid By substituting 4-mercaptobutanoyl-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 97, 1-[4-lethyldithio-butanoyl]-L-pipecolic acid is obtained.
Example 108 ..... _ :
1-[3-(Ethyldithio)propanoyl]-5-hydroxy-L-pipecolic acid By substituting 1-(3-mercaptopropanoyl)-5-hydroxy-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 97, 1-[3-(ethyldithio)propanoyl]-5-hydroxy-L-pipecolic acid :is obtained.
~ ,~q3 Example 109 1-[3-[(2-Amino-2-carboxyethyl)dithio]propanoyl]-L-proline A 0.5 M solution of thiocyanogen in glacial acetic acid is prepared by shaking Eor ten minutes in a sealed ~lask 600 mg of dry lead thiocyanate with a solution of 75 ~1 of bromine in 3 ml of acetic acid. After removal of lead bromide and excess lead thiocyanate by centrifugation, 2.5 ml of this solution is mixed with 2.5 ml of a 0.41 M solution of cysteine hydrochloride previously neutralized with dilute sodium hydroxide. This mixture is immediately added to 0.75 ml of a 1~9 M solution of 3-mercaptopropanoyl-L-proline previously neutralized with dilute sodium hydroxide. After twenty minutes the mixture is titrated to incipient brown color with alcoholic iodine, and adjusted to pH 3. The precipitate is removed by filtration and the filtrate is applied to a column of cation exchange resin (Dowex 50). The column is washed with water until no more acidic material is removed and then eluted with pyridine-acetate buffer pH 6Ø
The fractions containing the disulfide of cysteine and 3-mercaptopropanoyl-L-proline are pooled and concentrated to dryness.
Example 110 1,1'-[Dithiobis)4-propanoyl)]-bis-L-proline 3-Mercaptopropanoyl-L-proline (0.95 g) is dissolved in water (20 ml) and the pH is adjusted to 6.5 with N-sodium hydroxide. An ethanolic solution of iodine is added drop-wise while maintaining the pH at 6.5 with careful addition of N sodium hydroxide. When a permanent yellow color is obtained the addit:ion of iodine is stopped and the color '~
~u~
is discharged ~ith a small amount of sodium thiosulfate.
The reaction mixture is clcidified wi-th concen-trated hydro-chloric acid and e~tracted with ethyl aceta-te. The organic phase is washed with water, dried and concentrated to dryness to yield l,l'-[dithiobis(3-propanoyl)]-bis-L-proline. The di-cyclohe~ylammonium salt is prepared by addition of dicyclo-hexylamine to a solution of the free acid in acetonitrile, m.p. 179-180.
Example 111 1,1'-1Dithiobis(2-D-methyl-3-propanoyl)]-bis-L-proline By substituting 3-mercapto-2-D-methylpropanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-D-methyl-3-propanoyl)]-bis-L-proline is obtained, m.p. 236-237.
Example 112 1,1'-rDithiobis(2-propanoyl)-bis-L-proline By substituting 2-mercaptopropanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110 1,1'-1dithiobis)2-propanoyl~]-bis-L-proline is obtained.
Example 113 l,l'-(Dithiobisacetyl)-bis-L-hydroxy proline By substituting 1-(2-mercaptoacetyl)-L-hydroxyproline for the 3-mercaptopropionyl-L-proline in the procedure of Example 110, l,l'-(dithiobisaeetyl)-bis-L-hydroxyproline is obtained.
Example 114 1,1'-(Dithiobisacetyl)-bis-L-azetidine-2-carboxylic aeid By substituting 1-(2-mercaptoaeetyl)-L-azetidine-2-carboxylic acid for the 3-mereaptopropanoyl-L-proline in the proeedure of Example 110, l,l'-(dithiobisaeetyl)-bis-L-azetidine-2-carboxylic acid is obtained.
Ex mple 115 1,1'-[Dithiobis(3-propanoyl)]-bis-L-pipecolic acid sy substituting 3-mercaptopropanoyl-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(3-propanoyl)]-bis-L-pipecolic acid is obtained.
Example 116 1,1'-[Dithiobis(3-propanoyl)]-bis-4-methyl-L-proline By substituting 1-(3-mercaptopropanoyl)-4-methyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobist3-propanoyl)]-bis-4-methyl-L-proline is obtained.
Example 117 1,1'-[Dithiobis(3-propanoyl)]-bis-5-hydroxy-L-pipecolic acid By substituting 1-(3-mercaptopropanoyl)-5-hydroxy-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the pro-cedure of Example 110, 1,1'-[dithiobis(3-propanoyl)]-bis-5-hydroxy-L-pipecolic acid is obtained.
Example 11~
1,1'-[Dithiobis(2-benzyl-3-propanoyl-)]-bis-L-proline , ;
By substituting 1-(3-mercapto-2-benzylpropanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-benzyl-3-propanoyl)]-bis-L-proline is obtained.
`:
Example 119 1,1'-[Dithiobis)2-methyl-3-propanoyl)]-bis-L-pipecolic acid By substituting 1-(3-mercapto-2-methylpropanoyl)-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-methyl-2-propanoyl)]-bis-L-pipecolic acid is obtained.
Example 120 1,1'-[Dithiobis)4-butanoyl)]-bis-L--proline By substituting 4-mercaptobutanoyl-L-proline for the lQ 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(4-butanoyl)]-bis-L-proline is obtained.
- Example 121 1,1'-[Dithiobis(2-benzyl-4-butanoyl)]-bis-L-proline By substituting 1-(4-mercapio-2-benzylbutanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-~dithiobis(2-benzyl-4-butanoyl)]-bis-L-proline is obtained.
Example 122 1 t 11- [Dithiobis(3-butanoyl)]-bis-L-proline By substituting 3-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(3-butanoyl)]-bis-L-proline is obtained.
~ .
4~ "5~
Example 123 1,1'-[Dithiobis(3-propanoyl)]-bis-I.-proline methyl ester A solution of 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in methanol is treated with ethereal diazomethane until persistent yellow color. After fif-teen minutes a fe~ drops of acetic acid are added and the solvents are removed ln vacuo to yield, l,l'-[dithiobis(3-propanoyl)]-bis-L-proline methyl ester.
Example 124 1,1'-[Dithiobis(3-propanoyl)]-bis-L-proline amide A solution of 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline methyl ester in methanol is saturated with am-monia ~hile cooling in an ice-water bath. The reaction mixture is stored for 16 hours at room temperature in a pressure bottle, and then the solvents are removed in vacuo to yield l,l'-[dithiobis(3-propanoyl)]-bis-L-proline amide.
Example 125 1,1'-[Dithiobis(2-phenyl-3-propanoyl)]-bis-L-proline By substituting 1-(3-mercapto-2-phenylpropanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-phenyl-3-pro-panoyl)]-bis-L-proline is obtained.
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Example 126 1,1'-[(Sulfinylthio)-bis-(3-propanoyl)]-bis-L-pr_line While cooling in an ice bath 0.12 mole of peracetic acid is added to a stirred solution of l,l'-[di-thiobis(3-propanoyl)]-bis-L-proline (40 g) in glacial acetic acid (500 ml). The reaction mixture is allowed to stand over-night at room temperature and the solvent is then removed _ vacuo to yield 1,1'-[(sulfinylthio)-bis-(3-propanoyl)]-bis-L-proline.
Example 127 1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-L-proline A 30~ solution of hydrogen peroxide (2.0 ml) is added to a solution of l,l'-[dithiobis(3-propanoyl)]-bis-L-proline (4 g) in glacial acetic acid (80 ml) and the solution is stored for thirty hours at room temperature.
The solvent is removed in vacuo to yield l,l'-[(sulfonyl-thio)-bis-(3-propanoyl)]-bis-L-proline.
Example 128 1,1'-[(Sulfinylthio)-bis-(2-propanoyl)]-bis-L-proline By substituting 1,1'-[dithiobis(2-propanoyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-propanoyl)]-bis-L-proline is obtained.
62 , !
~, ~1.}~
Example 129 1,1'-[(Sulfinylthio)-bis-acetyl]-bis-L-azetidine-2-carboxy-lic acid By substituting l,l'-(dithiobisacetyl)-bis-L-azeti-dine carboxylic acid for the l,l'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-acetyl]-bis-L-azetidine-2-carboxylic acid is obtained.
Example 130 1,1'-[(Sulfinylthio)-bis-(3-propanoyl)]-bis-4-methyl-L-proline By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-4-methyl-L-proline for the 1,1'-[dithiobis(3-propanoyl)~-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(3-propanoyl)]-bis-4-methyl-L-proline is obtained.
Example 131 1,1'-[(Sulfinylthio)-bis-(2-benzyl-3-propanoyl)]-bis-L-proline By substituting 1,1'-[dithiobis(2-benzyl-3-propa-noyl)~-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)~-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-benzyl-3-propanoyl)]-bis-L-proline is obtained.
Example 132 l,l'-[(Sulfinylt~ ~
~y substituting 1,1'-[dithiobis(4-butanoyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sulfinyl-thio)-bis-(4-butanoyl)]-bis-L-proline is obtained.
~Ji3~
_ample 133 1,1'-[(Sulfinylthio)-bis-(3-butano~l)]-bis-L-proline __ By substituting 1,1'-[dithiobis(3-butanoyl)]-bis-L-proline for the l,l'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of E~ample 126, 1,1'-[(sulfinylthio)-bis-(3-butanoyl)~-bis-L-proline is obt.ained.
Example 134 1,1'-[(Sulfinylthio)-bis-(2-methyl-3-propanoyl)-bis-L-pro-line By substituting 1,1'-[dithiobis(2-methyl-3-propan-oyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-proline is obtained.
Example 135 1,1'-[(Sulfinylthio)-bis-(2-phenyl-3-propanoyl)]-bis-L-proline By substituting 1,1'-[dithiobis(2-phenyl-3-propa-noyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-phenyl-3-propanoyl)]-bis-L-proline is obtained.
Example 136 1-[3-[[3-(2-Carboxy-l-pyrrolidinyl)-3-oxopropyl~-dithio]-2-methylpropanoyl]-L-proline By substituting 1,1'-[(sulfinylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-proline for the ethylthiosulfinate in the procedure of Example 97, 1 [3-[[3-(2-carboxy-1-pyrro-lidinyl)-3-oxopropyl]dithio]-2-methylpropanoyl]-L-proline is obtained.
E p e 137 l,l'-[(Sulfonylthio)-bis-acetyl)-bis-L-hydroxyproline By substituting l,l'-(dithiobisacetyl)-bis-L-hy-droxy proline for the l,l'-[dithiobis(3-propanoyl)-bis-L-proline in the procedure of Example 127, l,l'-[(sulfonyl-thio)-bis-acetyl)-bis-L-hydroxyproline is obtained.
Example 138 1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-L-pipecolic acia By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-L-pipecolic acid for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 127, l,l'-[(sul-fonylthio)-bis-(3-propanoyl)]-bis-L-pipecolic acid is ob-tained.
Example 139 1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-5-hydroxy-L-pipecolic acid By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-
trated to dryness to obtain 4-bromo-2-methylbutanoic acid.
Example 47 1-(4-Benzoylthio-2-methylbutanoyl)-l-Proline a) 4-sromo-2-methylbutanoic acid (8 g.) and thionyl chloride (7 g.) are mixed and the mixture is stirred for 16 hours at room temperature. The reaction mixture is concentrated to dryness and distilled in vacuo.
b) To a solution of L-proline (2.88 g.) in normal sodium hydroxide (25 ml.) chilled in an ice bath, 2N sodium hydroxide (12.5 ml.) and the 4-bromo-2-methylbutanoic acid chloride ob,ained in part (a) (3.9 g.) are added. The reaction mixture is stirred at room temperature for 3.5 hours and a suspension of thiobenzoic acid (3.75 g.) and potassium carbonate (2.4 g.) in water (25 ml.) is added. After overnight stirring at room temperature, the reaction mixture is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and concentrated to dryness in vacuo. The residue is chromatographed on a column of silica gel with benzene-acetic acid (7:1). The fractions containing the desired product, 1-(4-benzoylthio-2-methylbutanoyl)-L-proline are pooled and concentrated to dryness in vacuo.
Example 48 1-(4-Mercapto-2-methylbutanoyl)-L-Proline _ By substitu1ting 1-(4-benzoylthio-2-methylbutanoyl)-L-proline for the L-(4-benzoylthiobutanoyl)-L-proline in the procedure of Example 45, 1-(mercapto-2-methylbutanoyl)-L-proline in obtained.
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Example 49 4-sromo-2-benzylbutanoic acid By substituting ethyl-4-bromo-2-benzylbutanoate [prepared by the procedure of G. Jones and J. Wood lTetrahedron, 21, 2961 (1965) starting with diethylbenzylmalonate]] for the ethyl-4-bromo-2-methylbutanoate in the procedure of Example 46, 4-bromo-2-benzylbutanoic acid is obtained.
Example 50 1-(4-Benzoylthio-2-benzylbutanoyl)-L-Proline By substituting 4-bromo-2-benzylbutanoic acid for the 4-bromo-2-methylbutanoic acid in the procedure of Example 47, 1-(4-benzoylthio-2-benzylbutanoyl)-L-proline is obtained.
Example 51 1-(4-Mercapto-2-benzylbutanoyl)-L-Proline By substituting 1-(4-benzoylthio-2-benzylbutanoyl)-L-proline for the l-(4-benzoylthiobutanoyl)-L-proline in the procedura of Example 45, 1-(mercapto-2-benzylbutanoyl)-L-proline is obtained.
Example 52 1-(4-Mercaptobutanoyl)-L-Hydroxyproline By substituting L-hydroxyproline for the L-proline in the procedure of Example 44 and subjecting the product to ammonolysis as in Example 45, 1-(4-benæoylthiobutanoyl)-L-hydroxy-proline and l-(4-mercaptobutanoyl)-L-hydroxyproline, respectively, are obtained.
Example 53 1-(4-Mercaptobutanoyl)-L-Azetidine-2-Carboxylic Acid By substituting L-azetidine-2-carboxylic acid for the L-proline in the procedure of Example 44 and subjecting the product to ammonolysis as in Example 45, l--(4-benzoylthio-butanoyl)-L-azetidine-2-carbo~ylic acid and l-(4-mercapto-butanoyl)-L-azetidine-2-carboxylic acid, respectively, are obtained.
Example 54 1-(4-Mercaptobutanoyl)-L-Pipecolic Acid _ _ By substituting L-pipecolic acid for the L-proline in the procedure of Example 44 and subjecting the product to ammonolysis as in Example 45, l-(4-benzoylthiobutanoyl)-L-pipecolic acid and 1-(4-mercaptobutanoyl)-L-pipecolic acid, respectively, are obtained.
Example 55 l-(3-Acetylthiobutanoyl)-L-Proline tert-butyl Ester Dicyclohexylcarbodiimide (6.2 g.) and 3-acetylthio-butyric acid (4.86 g.) are added to a solution of L-proline tert-butyl ester (5.1 g.) in dichloromethane (60 ml.) stirred in an ice bath. After 15 minutes the ice bath is removed and the mixture is stirred at room temperature for 16 hours.
The precipitate is filtered, the filtrate is concentrated to dryness and the residue is chromatographed on a column of silica gel with chloroform to obtain 1-(3-acetylthiobutanoyl)-L-proline tert-butyl ester, yield 5.2 g.
Example 56 1-~3-Acetylthiobutanoyl)-L-Proline _ .
The 1-(3-acetylthiobutanoyl)-L-proline tert-butyl ester of Example 55 (5.2 g.) is dissolved in a mixture of trifluoro-acetic acid (60 ml.) and anisole (30 ml.) and the solution is kept at room temperature for one hour. The solvents are removed in vacuo and the residual l-(3-acetylthiobutanoyl)-L-proline is reprecipitated from ether-hexane several times, yield .
4 g.. The dicyclohexylamine salt is made by the procedure of Example ~4, m.p. 175-176.
Example 57 1-(3-Mercaptobutanoyl)-L-Proline The 1-(3-acetylthiobutanoyl)--L-proline of Example 56 (0.86 g.) is dissolved in 5.5 N. methanolic ammonia (20 ml.) and the reaction mixture is stored at room temperature for 2 hours. The solvent is removed in vacuo and the residue chromatographed on an ion exchange column (Dowex 50) with water. The fractions containing the desired 1-(3-mercaptobutanoyl)-L-proline are pooled and lyophilized, yield 0.6 g. The dicyclohexylamine salt is produced by the procedure of Example 44, m.p. 183-184.
Example 58 1-[3-[[(Ethoxy)carbonyl]thio]propanoyl]-L-proline Ethyl chloroformate (1.2 g.) is added to a solution of 3-mercaptopropanoyl-L-proline (2.03 g.) in normal sodium bicar-bonate (30 ml.) and the mixture is stirred vigorously at 5 ~or one hour, and for two hours at room temperature. ~fter acidification with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. The organic phase is washed with water, dried over magnesium sulfate, and concentra-ted to dryness to yield l-[3-[[(ethoxy)carbonyl]thio]propanoyl]-L-proline.
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Example 59 1-[3-[[(Ethoxy)thiocarbonyl]thio]propanoyl]-L-proline Aqueous 2N sodium hydroxide ~25 ml) and 3-bromopropionyl chloride (8.5 g) are added to a solution of L-proline (5.75 g) in N sodium hydroxide (50 ml) chilled and stirred in an ice bath. After five minutes the ice bath is removed and the stirring is continued at room temperature. After three hours ethyl xantogenic acid potassium salt (9.6 g) is added and the mixture is stirred overnight at room temperature. The solution is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is concentrated to dry-ness and the residue is chromatographed on a column of silica gel with a mixture of benzene-acetic acid (7:1) as solvent, to yield 1-[3-[[(ethoxy)thiocarbonyl]thio]propanoyl]-L-proline, m.p. 94-95.
Example 60 1-[3-[[(Benzylthio)carbonyl]thio]propanoyl]-L-proline A solution of benzylthiocarbonyl chloride (11 ml) in dioxane (20 ml) is added in five portions to a solution of 1-(3-mercaptopropanoyl)-L-proline (1.6 g) in normal sodium bicarbonate (24 ml) chilled in an ice bath, over a period of 30 minutes. The ice bath is removed and the stirring is continued for 2.5 hours at room temperature. After acid-ification with concentrated hydrochloric acid, the aqueous phase is extracted with eth~l acetate. The organic phase is dried over magnesium sulfate and concentrated to dryness to yield 1-[3-[~(benzylthio)carbonyl]thio]propanoyl]-L-proline.
, `''~ 1, ;` : , Example 61 1-[3-[[(Ethylthio)thiocarbonyl]thio]propanoyl]-l-proline Aqueous 2N sodium hydroxide (25 ml) and 3-bromopropionyl chloride (8.5 g) are added to a solution of L-proline (5.75 g) in N sodium hydroxide (50 ml) chilled and stirred in an ice bath. After five minutes, the ice bath is removed and the stirring is continued at room temperature. After three hours, ethyl trithiocarbonate potassium salt (10.5 g) is added and the mixture is stirred at room temperature overnight. After aeidification with concentrated hydrochloric acid, the mixture is extracted with ethyl acetate. The organic layer is dried over magnesium sulfate and concentrated to dryness to yield 1-~3-[[(ethylthio~hioearbonyl]thio]propanoyl]-~-proline.
Example 62 3-[[(Methylamino)thiocarbonyl]thio]propionic acid Methylisothiocyanate (4 g) is added to a solution of 3-mereaptopropionie aeid (5.3 g) in a mixture of pyridine (250 ml) and 0.5 N sodium hydroxide (100 ml). The solution is kept at 40 for two hours and eoneentrated to dryness in vacuo. The residue is dissolved in water (100 ml.), aeidified with concentrated hydrochloric acid and extraeted with ether. The organie phase is concentrated to dryness to yield 3-[[(methylamino)thiocarbonyl]thio]propionic acid, m.p. 86-87.
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E~ample 63 _ 1-[3-[[(Methylamino)thiocarbonyl]thio]pr~ yl~
tert-butyl ester To a solution of L-proline tert-butyl ester (1.71 g) and hydroxybenzotriazole (1.35 g) in dichloromethane (10 ml) chilled and stirred in an ice bath, dicyclohexylcarbodiimide (2.06 g) and 3-methylaminothiocarbonylthiopropionic acid (1.79 g) are added. After 15 minutes, the bath is removed and the stirring is continued overnight. The precipitate is filtered off and the filtrate is diluted with ethyl acetate and washed neutral.
The organic phase is concentrated to dryness to yield 1-~3-t[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline tert-butyl ester, m.p. 129-130.
Example 64 1-13-[[(Methylamino)thiocarbonyl]thio]propanoyl]-L-proline A) l-(Methylaminothiocarbonylthiopropanoyl)-L-proline tert-butyl ester (0.98 g) is dissolved in a mixture of anisole (3.6 ml) and trifluoroacetic acid (7.5 ml). After one hour at room temperature the mixture is concentrated to dryness in vacuo and the residue precipitated from ether-hexane three times. This material is chromatographed on a column of silica gel with a solvent mixture of benzene-acetic acid (75:25) to yield 1-[3-[[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline, Rf = 0.4 [silica gel-benzene:acetic acid (75:25)]. The , dicyclohexylammonium salt has m.p. 127-129.
;, I
s) ~lethylisothiocyanate (4 g) is added to a solution of 3-mercaptopropanoyl-L-proline (10.1 g) in a mixture of pyridine (250 ml) and 0.5 N sodium hydroxide (100 ml). The solution is kept at 40 for two hours and concentrated to dryness ln vacuo.
The residue is dissolved in water (100 ml), acidified with con-centrated hydrochloric acid and extracted with ethyl acetate.
The organic phase is concentrated to dryness to yield 1-[3-[[(methylamino)thiocarbonyl]thio]propanoyl]-L-proline.
Example 65 1-[3-r[(Ethylamino)carbonyl]thio]propanoyl]-L-proline Ethylisocyanate ~0.45 ml) is added to a solution of 1-(3-mercaptopropanoyl)-L-proline (1 g) in a mixture of N
sodium hydroxide (5 ml) and pyridine (5 ml). The solution is heated at 40 for four hours and concentrated in vacuo.
The residue is distributed between 0.1 N hydrochloric acid and ethyl acetate. The organic layer is washed with water, dried over magnesium sulfate and concentrated to dryness to yield l-[3-[[(ethylamino)carbonyl]thio]propanoyl]-L-proline.
The dicyclohexylammonium salt is prepared by adding dicyclo-hexylamine to a solution of the free acid in ethyl acetate,m.p. 150-152.
Example 66 .
1-[3-[1(Ethoxy)carbonyl]thio]-2-methylpropanoyl]-L-proline By substituting 1-(3-mercapto-2-methylpropanoyl]-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 58, 1-[3-[[(ethoxy)carbonyl]thio]-2-methylpropanoyl]-L-proline is obtainecl.
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xample 67 1-[3-[l(Ethoxy)carbonyl]_hio]butanoyl~-L-proline By substituting 1-(3-mercaptobutanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 58, 1-[3-[[(ethoxy)carbonyl]thio]butanoyl]-L~pro-line is obtained.
Example 68 1-[3-[l(Ethoxy)thiocarbonyl]thio~propanoyl]-L-azetidine-2-carboxylic acid By substituting L-azetidine-2-carboxylic acid for L-proline in the procedure of Example 59, 1-[3-[l(ethoxy)-thiocarbonyl]thio]propanoyl]-L-azetidine-2-carboxylic acid is obtained.
Example 69 1-13-11(Ethoxy)thiocarbonyl]thio]propanoyl]-L-pipecolic acid By substituting L-pipecolic acid for L-proline in the procedure of Example 59, 1-[3-[[(ethoxy)thiocarbonyl]-thio]propanoyl]-L-pipecolic acid is obtained.
Example 70 1-14-[[(Benzylthio)carbonyl]thio]butanoyl]-L-proline By substituting 4-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 60, 1-[4-[l(benzylthio)carbonyl]thio]butanoyl]-L-proline is obtained.
Example 71 1-[2-[[(Benzylthio)carbonyl]thio]propanoyl~-L-proline By substituting 2-mercaptopropanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 60, 1-[2-[[(benzylthio)carbonyl]thio]propanoyl]-L-proline is obtained.
~ .' .
Example 72 1-[3-[[(Ethylthio)thiocarbonyl]-thio~propanoyl]-L-proline methyl . .
ester A solution of 1-[3-[[(e-thylthio)thiocarbonyl]thio]-propanoyl]-L-proline in ethyl acetat.e is treated with an ethereal solution of diazomethane until persi.stent yellow color. Af-ter discharging the yellow color with a few drops of acetic acid, the solvents are removed in vacuo to yield l-[3-[[(ethylthio)-thiocarbonyl]thio]propanoyl]-L-proline methyl ester.
Example 73 1-[3-[[(methylamino)thiocarbonyl]thio]propanoyl]-5-hydroxy-L-pipecolic acid By substituting 1-(3-mercaptopropanoyl)-5-hydroxy-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the Procedure B of Example 64, 1-[3-[[(methylamino)thiocarbonyl]thio]-propanoyl]-5-hydroxy-L-pipecolic acid is obtained~ ¦
Example 74 l-t3-[[(Methylamino)thiocarbonyl]thio]-2-methylpropanoyl]-L-proline amide By substituting l-t3-mercapto-2-methylpropanoyl)-L-proline amide for the 3-mercaptopropanoyl-L-proline in the Procedure B of Exanple 64, 1-[3-[[(methylamino)thiocarbonyl]thio]- ' 2-methyl-propanoyl]-L-proline amide is obtained.
Example 75 1-[3-[[(Phenoxy)carbonyl]thi_]propanoyl]-L-proline By substituting phenylchloroformate for ethyl chloroformate in the procedure of Example 58, 1-[3-[[(phenoxy)carbonyl]thio]-propanoyl]-L-proline is obtained.
Example 76 1-[3-[[(Phenoxy)carbonyl]thio]butan_yl]-L-p oline By substituting phenylchloroformate for the e~hyl chloroformate and 4-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 58, 1-[3-~[(phenoxy)carbonyl]thio]butanoyl]-L-proline is obtained.
Example 77 1-[3-[[(Phenylamino)carbonyl]thio]propanoyl]-L-proline By substituting phenylisocyanate for the ethylisocyanate in the procedure of Example 65, 1-[3-[[(phenylamino)carbonyl]-thio]propanoyl]-L-proline is obtained.
Example 78 1-[3-[[(Phenethylamino)carbonyl]thio]propanoyl]-L-proline By substituting phenethylisocyanate for the ethylisocyanate in the procedure of Example 65, 1-[3-1[(phenethylamino)carbonyl]-thio]propanoyl]-L-proline is obtained.
Example 79 1-13-[~(Ethylamino)carbonyl]thio]-2-benzylpropanoyl]-L-proline By substituting 1-(3-mercapto-2-benzylpropanoyl)-L-proline for the l-(3-mercaptopropanoyl)-L-proline in the procedure of Example 65, 1-[3-[[(ethylamino)carbonyl]thio]-2-benzylpropanoyl]-L-proline is obtained.
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Example 80 1-(3-Methylthiopropanoyl ? -L-proline A) ~lethyl 3-methylthiopropionate (51 g) is saponi~ied with a lOQ sodium hydroxide solution (150 ml, 30 minutes at 100).
The cooled solution is extracted with ether and then acidified.
The crude acid thus obtained is distilled and converted to the acid chloride with thionyl chloride.
A solution of L-proline (11.5 g) in N sodium hydroxide (100 cc) is chilled in an ice bath and the 3-methylthiopropanoic acid chloride (6.9 g) is added dropwise with vigorous stirring over a ten minutes period. After five hours the reaction mixture is acidified and extracted with ethyl ether to yield 1-(3-methylthiopropanoyl)-L-proline. The dicyclohexylammonium salt is prepared by adding dicyclohexylamine to a solution of the free acid in ethyl acetate, m.p. 169-171.
~) Methyl iodide (71 g) is added to a solution of 1-(3-mercaptopropanoyl)-L-proline ethyl ester (115 g) and sodium (11.5 g) in ethanol (400 ml). The reaction is allowed to proceed overnight, the ethanol is removed in vacuo and the residue is dissolved in a mixture of ethyl acetate and water.
The organic layer is dried and concentrated to dryness in vacuo.
The resulting 1-(3-methylthiopropanoyl)-L-proline ethyl ester (98 g) is suspended in a mixture of methanol (200 ml) and 5 N
sodium hydroxide (200 ml) and stirred at room temperature for five hours. The methanol is removed in vacuo, and the aqueous phase is extracted with ethyl acetate, acidified and reextracted with ethyl acetate. This last organic phase is washed with water, dried and concentrated to dryness to yield l-(3-methylthio-prGpanoyl)-L-proline.
!
Example 81 1-[3-(4-Chlorophenylthio)propanoyl]-L-proline Aqueous 2 N sodium hydroxide (25 ml) and 3-bromopropionyl chloride (8.5 g) are added to a solution of L-proline (5.75 g) in N-sodium hydroxide (50 ml) chilled and stirred in an ice bath. After five minutes, the ice bath is removed and the stirring is continued for three hours at room temperature. The reaction mixture is acidified with concentrated hydrochloric acid ~nd extracted with ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness in vacuo. The residue is dissolved in a mixture of 4-chlorobenzenethiol (8 g), sodium hydroxide (4.2 g) and ethanol (300 ml). The solution is re~luxed for 6 hours. The solvent is removed in vacuo and the residue is dissolved in water, acidified with concentrated hydro-chloric acid and extracted with ethyl acetate. The organic layer is washed with water, dried, and concentrated to dryness in vacuo to yield l-[3-(4-chlorophenylthio)propanoyl]-L-proline.
Ex mple 82 ~ (3-Benzylthiomethyl)thio]propanoyl]-L-proline 1-(3-Mercaptopropanoyl)-L-proline (8.1 g) is dissolved in boiling liquid ammonia (100 ml) and small pieces of sodium are added until permanent blue color is obtained which is then discharged with a small piece of ammonium chloride. Benzyl-thiomethyl chloride (6.9 g) is added and the ammonia is allowed to evaporate. The final traces of ammonia are removed in vacuo, the residue is dissolved in water and extracted with ethyl acetate. The aqueous phase is acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness ~Y
to yield 1-~[(3-benz~lthiomethyl)-thio]propanoyl]-L-proline.
Example 83 1-[[(3-Acetamidomethyl)thio]propanoyl]-L-proline 1-(3-Mercaptopropanoyl)-L-proline (2 g) and N-hydroxy-methylacetamide (0.89 g) are dissolved in trifluoroacetic acid (10 ml) and the solu-tion is stored at room temperature for one hour. The excess tirfluoroacetic acid is removed in vacuo and the residue is precipitated several times from ether-hexane.
Finally, the residue is distributed between dilute hydrochloric acid and ethyl acetate. The organic layer is washed with water, dried and concentrated to dryness to yield l-[[3-acetamido-metnyl)thio]propanoyl]-L-proline.
Example 84 l-(~Iethylthioacetyl)-L-proline By substituting methyl methylthioacetate for the methyl 3-methylthiopropionate in the Procedure A of Example 80, 1-(methylthioacetyl)-L-proline, m.p. 123-124, is obtained.
` Example 85 l-(Benzylthioacetyl)-L-proline ~y substituting benzylthioacetyl chloride for the 3 methylthiopropanoyl chloride in the Procedure A of Example 80, l-(benzylthioacetyl)-L-proline, m.p. 86-88, is obtained.
, E~ample 86 1-[3-[(2-Pheny~ethyl)thio]propanoyl]-L-proline By substituting phenethylbromide for the methyl io-dide in the Procedure B of Example 80, 1-[3-[(2-phenyl-ethyl)thio]propanoyl]-L-proline is obtained.
Example 87 1-[3-[tTriphenylmethyl)thio]propanoyl]-L-proline By substituting triphenylmethyl chloride for the methyl iodide in the Procedure B of Example 80, 1-[3-[(triphenylmethyl)thio]propanoyl]-L-proline is obtained.
Example 88 1-(3-Methylthio-2-methylpropanoyl)-L-proline amide By substituting 1-(3-mercapto-2-methylpropanoyl)-L-proline amide for the l-(3-mercaptopropanoyl)-L-proline ethyl ester in the Procedure B of Example 80 and elimina-ting the saponification step, l-(3-methylthio-2-methylpro-panoyl)-L-proline amide is obtained.
Example 89 1-(3-Methylthiopropanoyl)-L-azetidine-2-carboxylic acid By substituting L-azetidine-2-carboxylic acid for the L-proline in the Procedure A of Example 80, 1-(3-methylthiopropanoyl)-L~azetidine-2-carboxylic acid is obtained.
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E~ample 90 1-[3-(4-Me-thoxyphenylthio)propanoyl]-L-proline sy substituting 4-methoxybenzenethiol for the 4-chloro-benzenethiol in the procedure of Example 81, 1-[3-(4-methoxy-phenylthio)propanoyl]-L-proline is obtained.
Example 91 1-13-Methylthiopropanoyl)-L-pipecolic acid By substituting L-pipecolic acid for the L-proline in the Procedure A of Example 80, 1-(3-methylthiopropanoyl)-L-pipecolic acid is obtained.
Example 92 1-[2-(4-Chlorophenylthio propanoyl]-L-proline By substituting 2-bromopropionyl chloride for the 3-bromopropionyl chloride in the procedure of Example 81, 1-[2-(4-chlorophenylthio-propanoyl]-L-proline is obtained.
Example`93 1-13-[(Diphenylmethyl)thio]-2-benzylpropanoyl)]-L-proline Diphenylmethanol (0.92 g) and 1-(3-mercapto-2-benzyl-propanoyl)-L-proline (1.5 g) are dissolved in trifluoroacetic acid (10 ml) and the solution-is kept at room temperature for 30 minutes. The excess trifluoroacetic acid is removed in vacuo to yield l-[3-[~diphenylmethyl)thio]-2-benzylpropanoyl]-L-proline.
.
Example 94 _ 1-[4-(4-Chlorophenylthio)butanoyl]-L-proiine sy substituting 4-bromopropionyl chloride for the 3-bromopropionyl chloride in the procedure of Example 81, 1-[4-(4-chlorophenylthio)butanoyl]-L-proline is obtained.
Example 95 1-[3-[(Benzylthiomethyl)thio]butanoyl]-L-proline By substituting 3-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 82, 1-13-[(benzylthiomethyl)thio]butanoyl]-L-proline is obtained.
Example 96 l-E[4-[(Acetamidomethyl)thio]-2-methylbutanoyl]-L-proline sy substituting 1-(4-mercapto-2-methylbutanoyl)-L-proline for the 1-(3-mercaptopropanoyl)-L-proline in the procedure of Example 83, 1-[[4-~acetamidomethyl)thio~-2-methylbutanoyl]-L-proline is obtained.
Example 97 1-[3-(Ethyldithio)propanoyl]-L-proline A) 3-Mercaptopropanoyl-L-proline (10 g) is added to a solution of ethylthiosulfinate (8.4 g) in methanol (100 ml) and the reaction mixture is stirred vigorously at room temperature for four hours. The methanol is removed in vacuo to yield 1-(3-ethyldithiopropanoyl)-L-proline.
B) A solution of ethylthiosulfinate (8.4 g) in ethanol (50 ml) i9 added to an aqueous solution of 3-mercapto-propanoyl-L-proline (10 g) maintained at pH 6-7 by careful addition of sodium hydroxide. The mixture is stirred vigorously at room temperature until negative thiol reaction. The mix-ture is diluted with water, adjusted to pH 8 and extracted with ethyl acetate, the aqueous phase i5 acidified to pH 3 and extracted again with ethyl acetate. This latter extract is washed with water, dried and concentrated to dryness to yield l-[3-~ethyldithio)propanoyl]-L-proline.
Example 98 1-13-[(4-Methylphenyl)dithio]propanoyl]-L-proline A solution of 4-methylphenylsulfenyl chloride (1.76 g.) in ether (20 ml) is added to a solution of 3-mercaptopropanoyl-L-proline (2 g) in 0.5 N sodium hydroxide (20 ml) chilled in an ice bath. The mixture is stirred vigorously for one hour, and the aqueous phase is separated, acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic phase is washed with water, dried and concentrated to dryness to yield 1-[[3-(4-methylphenyl)dithio]propanoyl]-L-proline.
Example 99 1-[3-(Phenyldithio-propanoyl]-L-proline By substituting phenylthiosulfinate [prepared from phenyl-disulfide according to U. Weber and P. Hartter, Z. Physiol. Chem.,351, 1384 (1970)] for the ethylthiosulfinate in the procedure of Example 97, 1-[3-~phenyldithio-propanoyl]-L-proline is obtained.
Example 100 1-[3-[(2-Phenylethyl)dithio]propanoyl]-L-proline By substituting 2-phenylethylthiosulfinate (prepared from phenethyldisulfide) for the ethylthiosuflinate in the procedure of Example 97, 1-[3-[(2-phenylethyl)dithio]propanoyl]-L-proline is obtained.
Example 101 1-[3-[(2-Hydroxyethyl)dithio]propanoyl]-L-proline To a solution of 1,1'-[(sulfinylthio)-bis-(3-propanoyl)]-bis-L-proline (21 g) in methanol (100 ml), mercaptoethanol(4.2 g) is added and the reaction mixture is stirred vigorously at room temperature for four hours. The methanol is removed in vacuo and the residue is pruified by chromatography on a silica gel column to yield 1-[3-[(2-hydroxyethyl)dithio]propanoyl]-L-proline.
Example 102 1-12-(Ethyldithio)propanoyl]-L-proline By substituting 2-mercaptopropanoyl-L-proline for 3-mercaptopropanoyl-L-proline in the procedure of Example 97, 1-[2-(ethyldithio)propanoyl]-L-proline is obtained.
Example`103 1-13-~(4-Methylphenyl)dithio]butanoyl]-L-proline By substituting 3-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 98, 1-[3-(4-methylphenyl)dithio]butanoyl]-L-proline is obtained.
Example 104 1-13-(Ethyldithio)-2-methylpropanoyl]-L-proline methyl ester _ By substituting 1-(3-mercapto-2-methylpropanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 97 and then treating the product with ethereal diazomethane as in the procedure of Example 72, 1-[3-(ethyldithio)-2-methylpro-panoyl]-L-proline methyl ester is obtained.
~,~
Example 105 1-[3-(Ethyldithio)propanoyl]-L-azetidine-2-carbo~ylic acid By subs-ti-tuting 3-mercaptopropanoyl-L-azetidine-2-carboxylic acid Eor the 3-mercaptopropanoyl-L-proline ln the procedure of Example 97, 1-[3-(ethyldithio)propanoyl]-L-aze-tidine-2-carboxylic acid is obtained.
Example 106 1-[3-~(4-Methylphenyl)dithio]-2-methylpropanoyl]-L-hydroxyproline By substituting 1-(3-mercapto-2-methylpropanoyl)-L-hydroxy proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 98, 1-[(3-[4-methylphenyl)dithio]-2-methylpropanoyl]-L-hydroxyproline is obtained.
Example 107 1-[4-tEthyldithio)butanoyl]-L-pipecolic acid By substituting 4-mercaptobutanoyl-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 97, 1-[4-lethyldithio-butanoyl]-L-pipecolic acid is obtained.
Example 108 ..... _ :
1-[3-(Ethyldithio)propanoyl]-5-hydroxy-L-pipecolic acid By substituting 1-(3-mercaptopropanoyl)-5-hydroxy-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 97, 1-[3-(ethyldithio)propanoyl]-5-hydroxy-L-pipecolic acid :is obtained.
~ ,~q3 Example 109 1-[3-[(2-Amino-2-carboxyethyl)dithio]propanoyl]-L-proline A 0.5 M solution of thiocyanogen in glacial acetic acid is prepared by shaking Eor ten minutes in a sealed ~lask 600 mg of dry lead thiocyanate with a solution of 75 ~1 of bromine in 3 ml of acetic acid. After removal of lead bromide and excess lead thiocyanate by centrifugation, 2.5 ml of this solution is mixed with 2.5 ml of a 0.41 M solution of cysteine hydrochloride previously neutralized with dilute sodium hydroxide. This mixture is immediately added to 0.75 ml of a 1~9 M solution of 3-mercaptopropanoyl-L-proline previously neutralized with dilute sodium hydroxide. After twenty minutes the mixture is titrated to incipient brown color with alcoholic iodine, and adjusted to pH 3. The precipitate is removed by filtration and the filtrate is applied to a column of cation exchange resin (Dowex 50). The column is washed with water until no more acidic material is removed and then eluted with pyridine-acetate buffer pH 6Ø
The fractions containing the disulfide of cysteine and 3-mercaptopropanoyl-L-proline are pooled and concentrated to dryness.
Example 110 1,1'-[Dithiobis)4-propanoyl)]-bis-L-proline 3-Mercaptopropanoyl-L-proline (0.95 g) is dissolved in water (20 ml) and the pH is adjusted to 6.5 with N-sodium hydroxide. An ethanolic solution of iodine is added drop-wise while maintaining the pH at 6.5 with careful addition of N sodium hydroxide. When a permanent yellow color is obtained the addit:ion of iodine is stopped and the color '~
~u~
is discharged ~ith a small amount of sodium thiosulfate.
The reaction mixture is clcidified wi-th concen-trated hydro-chloric acid and e~tracted with ethyl aceta-te. The organic phase is washed with water, dried and concentrated to dryness to yield l,l'-[dithiobis(3-propanoyl)]-bis-L-proline. The di-cyclohe~ylammonium salt is prepared by addition of dicyclo-hexylamine to a solution of the free acid in acetonitrile, m.p. 179-180.
Example 111 1,1'-1Dithiobis(2-D-methyl-3-propanoyl)]-bis-L-proline By substituting 3-mercapto-2-D-methylpropanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-D-methyl-3-propanoyl)]-bis-L-proline is obtained, m.p. 236-237.
Example 112 1,1'-rDithiobis(2-propanoyl)-bis-L-proline By substituting 2-mercaptopropanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110 1,1'-1dithiobis)2-propanoyl~]-bis-L-proline is obtained.
Example 113 l,l'-(Dithiobisacetyl)-bis-L-hydroxy proline By substituting 1-(2-mercaptoacetyl)-L-hydroxyproline for the 3-mercaptopropionyl-L-proline in the procedure of Example 110, l,l'-(dithiobisaeetyl)-bis-L-hydroxyproline is obtained.
Example 114 1,1'-(Dithiobisacetyl)-bis-L-azetidine-2-carboxylic aeid By substituting 1-(2-mercaptoaeetyl)-L-azetidine-2-carboxylic acid for the 3-mereaptopropanoyl-L-proline in the proeedure of Example 110, l,l'-(dithiobisaeetyl)-bis-L-azetidine-2-carboxylic acid is obtained.
Ex mple 115 1,1'-[Dithiobis(3-propanoyl)]-bis-L-pipecolic acid sy substituting 3-mercaptopropanoyl-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(3-propanoyl)]-bis-L-pipecolic acid is obtained.
Example 116 1,1'-[Dithiobis(3-propanoyl)]-bis-4-methyl-L-proline By substituting 1-(3-mercaptopropanoyl)-4-methyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobist3-propanoyl)]-bis-4-methyl-L-proline is obtained.
Example 117 1,1'-[Dithiobis(3-propanoyl)]-bis-5-hydroxy-L-pipecolic acid By substituting 1-(3-mercaptopropanoyl)-5-hydroxy-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the pro-cedure of Example 110, 1,1'-[dithiobis(3-propanoyl)]-bis-5-hydroxy-L-pipecolic acid is obtained.
Example 11~
1,1'-[Dithiobis(2-benzyl-3-propanoyl-)]-bis-L-proline , ;
By substituting 1-(3-mercapto-2-benzylpropanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-benzyl-3-propanoyl)]-bis-L-proline is obtained.
`:
Example 119 1,1'-[Dithiobis)2-methyl-3-propanoyl)]-bis-L-pipecolic acid By substituting 1-(3-mercapto-2-methylpropanoyl)-L-pipecolic acid for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-methyl-2-propanoyl)]-bis-L-pipecolic acid is obtained.
Example 120 1,1'-[Dithiobis)4-butanoyl)]-bis-L--proline By substituting 4-mercaptobutanoyl-L-proline for the lQ 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(4-butanoyl)]-bis-L-proline is obtained.
- Example 121 1,1'-[Dithiobis(2-benzyl-4-butanoyl)]-bis-L-proline By substituting 1-(4-mercapio-2-benzylbutanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-~dithiobis(2-benzyl-4-butanoyl)]-bis-L-proline is obtained.
Example 122 1 t 11- [Dithiobis(3-butanoyl)]-bis-L-proline By substituting 3-mercaptobutanoyl-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(3-butanoyl)]-bis-L-proline is obtained.
~ .
4~ "5~
Example 123 1,1'-[Dithiobis(3-propanoyl)]-bis-I.-proline methyl ester A solution of 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in methanol is treated with ethereal diazomethane until persistent yellow color. After fif-teen minutes a fe~ drops of acetic acid are added and the solvents are removed ln vacuo to yield, l,l'-[dithiobis(3-propanoyl)]-bis-L-proline methyl ester.
Example 124 1,1'-[Dithiobis(3-propanoyl)]-bis-L-proline amide A solution of 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline methyl ester in methanol is saturated with am-monia ~hile cooling in an ice-water bath. The reaction mixture is stored for 16 hours at room temperature in a pressure bottle, and then the solvents are removed in vacuo to yield l,l'-[dithiobis(3-propanoyl)]-bis-L-proline amide.
Example 125 1,1'-[Dithiobis(2-phenyl-3-propanoyl)]-bis-L-proline By substituting 1-(3-mercapto-2-phenylpropanoyl)-L-proline for the 3-mercaptopropanoyl-L-proline in the procedure of Example 110, 1,1'-[dithiobis(2-phenyl-3-pro-panoyl)]-bis-L-proline is obtained.
~) t~
Example 126 1,1'-[(Sulfinylthio)-bis-(3-propanoyl)]-bis-L-pr_line While cooling in an ice bath 0.12 mole of peracetic acid is added to a stirred solution of l,l'-[di-thiobis(3-propanoyl)]-bis-L-proline (40 g) in glacial acetic acid (500 ml). The reaction mixture is allowed to stand over-night at room temperature and the solvent is then removed _ vacuo to yield 1,1'-[(sulfinylthio)-bis-(3-propanoyl)]-bis-L-proline.
Example 127 1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-L-proline A 30~ solution of hydrogen peroxide (2.0 ml) is added to a solution of l,l'-[dithiobis(3-propanoyl)]-bis-L-proline (4 g) in glacial acetic acid (80 ml) and the solution is stored for thirty hours at room temperature.
The solvent is removed in vacuo to yield l,l'-[(sulfonyl-thio)-bis-(3-propanoyl)]-bis-L-proline.
Example 128 1,1'-[(Sulfinylthio)-bis-(2-propanoyl)]-bis-L-proline By substituting 1,1'-[dithiobis(2-propanoyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-propanoyl)]-bis-L-proline is obtained.
62 , !
~, ~1.}~
Example 129 1,1'-[(Sulfinylthio)-bis-acetyl]-bis-L-azetidine-2-carboxy-lic acid By substituting l,l'-(dithiobisacetyl)-bis-L-azeti-dine carboxylic acid for the l,l'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-acetyl]-bis-L-azetidine-2-carboxylic acid is obtained.
Example 130 1,1'-[(Sulfinylthio)-bis-(3-propanoyl)]-bis-4-methyl-L-proline By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-4-methyl-L-proline for the 1,1'-[dithiobis(3-propanoyl)~-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(3-propanoyl)]-bis-4-methyl-L-proline is obtained.
Example 131 1,1'-[(Sulfinylthio)-bis-(2-benzyl-3-propanoyl)]-bis-L-proline By substituting 1,1'-[dithiobis(2-benzyl-3-propa-noyl)~-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)~-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-benzyl-3-propanoyl)]-bis-L-proline is obtained.
Example 132 l,l'-[(Sulfinylt~ ~
~y substituting 1,1'-[dithiobis(4-butanoyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sulfinyl-thio)-bis-(4-butanoyl)]-bis-L-proline is obtained.
~Ji3~
_ample 133 1,1'-[(Sulfinylthio)-bis-(3-butano~l)]-bis-L-proline __ By substituting 1,1'-[dithiobis(3-butanoyl)]-bis-L-proline for the l,l'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of E~ample 126, 1,1'-[(sulfinylthio)-bis-(3-butanoyl)~-bis-L-proline is obt.ained.
Example 134 1,1'-[(Sulfinylthio)-bis-(2-methyl-3-propanoyl)-bis-L-pro-line By substituting 1,1'-[dithiobis(2-methyl-3-propan-oyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-proline is obtained.
Example 135 1,1'-[(Sulfinylthio)-bis-(2-phenyl-3-propanoyl)]-bis-L-proline By substituting 1,1'-[dithiobis(2-phenyl-3-propa-noyl)]-bis-L-proline for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 126, l,l'-[(sul-finylthio)-bis-(2-phenyl-3-propanoyl)]-bis-L-proline is obtained.
Example 136 1-[3-[[3-(2-Carboxy-l-pyrrolidinyl)-3-oxopropyl~-dithio]-2-methylpropanoyl]-L-proline By substituting 1,1'-[(sulfinylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-proline for the ethylthiosulfinate in the procedure of Example 97, 1 [3-[[3-(2-carboxy-1-pyrro-lidinyl)-3-oxopropyl]dithio]-2-methylpropanoyl]-L-proline is obtained.
E p e 137 l,l'-[(Sulfonylthio)-bis-acetyl)-bis-L-hydroxyproline By substituting l,l'-(dithiobisacetyl)-bis-L-hy-droxy proline for the l,l'-[dithiobis(3-propanoyl)-bis-L-proline in the procedure of Example 127, l,l'-[(sulfonyl-thio)-bis-acetyl)-bis-L-hydroxyproline is obtained.
Example 138 1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-L-pipecolic acia By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-L-pipecolic acid for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 127, l,l'-[(sul-fonylthio)-bis-(3-propanoyl)]-bis-L-pipecolic acid is ob-tained.
Example 139 1,1'-[(Sulfonylthio)-bis-(3-propanoyl)]-bis-5-hydroxy-L-pipecolic acid By substituting 1,1'-[dithiobis(3-propanoyl)]-bis-
5-hydroxy-L-pipecolic acid for the 1,1'-[dithiobis-(3-propanoyl)]-bis-L-proline in the procedure of Example 127, 1,1'-[(sulfonylthio)-bis-(3-propanoyl)]-bis-5-hydroxy-L-pipecolic acid is obtained.
Example 1~0 1,1'-[(Sulfonylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-pipecolic acid By substi-tuting 1,1'-[dithiobis~2-methyl-3-propa-noyl)]-bis-L-pipecolic acid for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 127, 1,1'-[(sulfonylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-pipecolic acid i!; obtained.
~1 .
' , E~ample 141 1,1'-[(Sulfonylthio)-bis-(2-benzyl-4-butanoyl)]-bis-L-proline By substitutin~ 1,1'-[dithiobis(2-benzyl-4-butan-onyl~]-bis-L-proline for the 1,1'-ldithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 127, l,l'-[(sul-fonylthio)-bis-(2-benzyl-4-butanoyl)]-bis-L-proline is ob-tained.
Example 142 3-Acetylthio-2-phenylpropanoic acid By substituting 2-phenylacrylic acid for the meth-acrylic acid in the procedure of Example 25, 3-acetylthio-2-phenylpropanoic acid is obtained.
1-(3-Acetylthio-2-phenylpropanoyl)-L-pro]ine tert-butyl ester By substituting 3-acetylthio-2-phenylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the proce-dure of Example 28, 1-(3-acetylthio-2-phenylpropanoyl)-L-proline tert-butyl ester is obtained.
Example 143 1-(3-Mercapto-2-phenylpropanoyl)-L-proline By substituting 1-(3-acetylthio-2-phenylpropanoyl)-L-proline tert-butyl ester for the 1-(3-acetylthio-2-methyl-propanoyl-L-proline tert-butyl ester in the pro-cedure of Example 29, and subjecting the product to am-monolysis as in Example 34, 1-(3-acetylthio-2-phenylpro-panoyl)-L-proline and 1-(3-mercapto-2-phenylpropanoyl)-L-proline are obtained.
135b ~ample 1~1~
1-[3-(Acetylthio)-DL-propanoyl¦pipecolic acid Pipecolic acid (6.5 g.) is suspended in 200 ml.
of dimethvlacetamide. 3-acetyl~hiopropanoyl chlor:ide ~8.3 g.) is added dropwise at ~3 to the suspension. A
clear solution forms and the temperature rises to 28 .
To this clear solution is added N-methylmorpholine (10.1 g.).
An immediate precipitate forms and the temperature rises to 34 . The mixture is heated on a steam bath for 1 hour when a clear solution forms. On cooling, the precipitated solid is filtered to yield 5.1 g. of 1-[3-(acetylthio)-DL-propanoyl]pipecolic acid, m.p. 190-200 . The solvent is removed and the viscous residue is triturated with isopropyl ether to yield 7.8 g. of product, m.p. 98-101 . Recrystalliza-tion from acetone-hexane yields a constant melting solid, m.p. 102-104 ; Rf 0.72 [silica gel, benzene, acetic acid (7:2)].
Example 145 DL-1-(3-Mercaptopropanoyl)pipecolic acid 12 ml. of concentrated ammonium hydroxide is stirred under nitrogen at 10 for about 15 minutes, then solid l-[3-(acetylthio)-DL-propanoyl]-pipecolic acid (6.6 g.) is added at 5 to 10 . A clear solution forms after 2-3 minutes. The ice bath is removed and the solution is stirred at room temperature under nitrogen for 45 minutes. The solution is made strongly acid with 20% HCl (cooling) and the precipitated oil is extracted with 3 x 150 ml. of ethyl acetate. The ethyl acetate extracts are dried over magnesium sulfate and the solvent is removed to yield 6.0 g. of DL-1-(3-mercaptopropanoyl)pipccolic acid, Rf 0.77 Isilica gel, ~nzene,acetic acid (7~
.
EIAl35b E:~ample l~G
l-(3-~1ercaptopropanoyl)~ pipecolic acid B$~ substituting L-pipecolic acid Eor the Dl.-pipecolic acid in the proceclure of Example l44 and then submitting the product to the procedure of Example 145, l-[3-(acetylthio)propanoyl~-L-pipecolic acid and l-(3-mercaptopropanoyl)-L-pipecolic acid Rf 0.80 [silica gel, benzene, acetic acid (7:1)], [~] -51.5 (c, l.0 abs.
ethanol), are obtained.
Example 147 l-~3-(Acetylthio)-2-methylpropanoyl-DL-pipecolic acid
Example 1~0 1,1'-[(Sulfonylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-pipecolic acid By substi-tuting 1,1'-[dithiobis~2-methyl-3-propa-noyl)]-bis-L-pipecolic acid for the 1,1'-[dithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 127, 1,1'-[(sulfonylthio)-bis-(2-methyl-3-propanoyl)]-bis-L-pipecolic acid i!; obtained.
~1 .
' , E~ample 141 1,1'-[(Sulfonylthio)-bis-(2-benzyl-4-butanoyl)]-bis-L-proline By substitutin~ 1,1'-[dithiobis(2-benzyl-4-butan-onyl~]-bis-L-proline for the 1,1'-ldithiobis(3-propanoyl)]-bis-L-proline in the procedure of Example 127, l,l'-[(sul-fonylthio)-bis-(2-benzyl-4-butanoyl)]-bis-L-proline is ob-tained.
Example 142 3-Acetylthio-2-phenylpropanoic acid By substituting 2-phenylacrylic acid for the meth-acrylic acid in the procedure of Example 25, 3-acetylthio-2-phenylpropanoic acid is obtained.
1-(3-Acetylthio-2-phenylpropanoyl)-L-pro]ine tert-butyl ester By substituting 3-acetylthio-2-phenylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the proce-dure of Example 28, 1-(3-acetylthio-2-phenylpropanoyl)-L-proline tert-butyl ester is obtained.
Example 143 1-(3-Mercapto-2-phenylpropanoyl)-L-proline By substituting 1-(3-acetylthio-2-phenylpropanoyl)-L-proline tert-butyl ester for the 1-(3-acetylthio-2-methyl-propanoyl-L-proline tert-butyl ester in the pro-cedure of Example 29, and subjecting the product to am-monolysis as in Example 34, 1-(3-acetylthio-2-phenylpro-panoyl)-L-proline and 1-(3-mercapto-2-phenylpropanoyl)-L-proline are obtained.
135b ~ample 1~1~
1-[3-(Acetylthio)-DL-propanoyl¦pipecolic acid Pipecolic acid (6.5 g.) is suspended in 200 ml.
of dimethvlacetamide. 3-acetyl~hiopropanoyl chlor:ide ~8.3 g.) is added dropwise at ~3 to the suspension. A
clear solution forms and the temperature rises to 28 .
To this clear solution is added N-methylmorpholine (10.1 g.).
An immediate precipitate forms and the temperature rises to 34 . The mixture is heated on a steam bath for 1 hour when a clear solution forms. On cooling, the precipitated solid is filtered to yield 5.1 g. of 1-[3-(acetylthio)-DL-propanoyl]pipecolic acid, m.p. 190-200 . The solvent is removed and the viscous residue is triturated with isopropyl ether to yield 7.8 g. of product, m.p. 98-101 . Recrystalliza-tion from acetone-hexane yields a constant melting solid, m.p. 102-104 ; Rf 0.72 [silica gel, benzene, acetic acid (7:2)].
Example 145 DL-1-(3-Mercaptopropanoyl)pipecolic acid 12 ml. of concentrated ammonium hydroxide is stirred under nitrogen at 10 for about 15 minutes, then solid l-[3-(acetylthio)-DL-propanoyl]-pipecolic acid (6.6 g.) is added at 5 to 10 . A clear solution forms after 2-3 minutes. The ice bath is removed and the solution is stirred at room temperature under nitrogen for 45 minutes. The solution is made strongly acid with 20% HCl (cooling) and the precipitated oil is extracted with 3 x 150 ml. of ethyl acetate. The ethyl acetate extracts are dried over magnesium sulfate and the solvent is removed to yield 6.0 g. of DL-1-(3-mercaptopropanoyl)pipccolic acid, Rf 0.77 Isilica gel, ~nzene,acetic acid (7~
.
EIAl35b E:~ample l~G
l-(3-~1ercaptopropanoyl)~ pipecolic acid B$~ substituting L-pipecolic acid Eor the Dl.-pipecolic acid in the proceclure of Example l44 and then submitting the product to the procedure of Example 145, l-[3-(acetylthio)propanoyl~-L-pipecolic acid and l-(3-mercaptopropanoyl)-L-pipecolic acid Rf 0.80 [silica gel, benzene, acetic acid (7:1)], [~] -51.5 (c, l.0 abs.
ethanol), are obtained.
Example 147 l-~3-(Acetylthio)-2-methylpropanoyl-DL-pipecolic acid
6.5 g. (0.05 m.) of pipecolic acid are suspended in dimethylacetamide (200 mg.), 9.0 g. (0.05 m.) of 3-acetylthio-2-methylpropanoyl chloride is added dropwise.
The temperature rises to 29 and a clear solution forms.
Then lO.l g. of N-methylmorpholine is added all at once and the temperature rises to 34 . The mixture is heated on a steam bath for l hour when a clear solution forms.
This is allowed to stand at room temperature overnight and the solid which precipitates is filtered to yield 6.1 g., m.p. 203-204 . The solvent is removed and the viscous residue is triturated with water and 20% HCl. The yellow oil is extracted with 3 x 150 ml. of ethyl acetate.
The ethyl acetate ex-tracts are dried over magnesium sulfate and removed to yield 14 g. of l-[3-(acetylthio)-2-methyl-propanoyl-DL--pipecolic acid as a viscous oil.
Example l~8 l-(3-Mercapto-2-methylpropanoyl)-DL-pipecolic acid Aqueous NE14011 (30 ml. water and 20 ml. conc. NH40H) is stirred under nitrogen at 10 Eor 15 minu-tes. This is -6~--~ ~3~ 5~
~1~135b I
added to 13.0 ~. (0.05 rn) of l-[3-(acetylthio)-2-methylpropanoyl]-DL-pipecolic acid and the resulting solution is stirred for lO minutes under nitrogen; then at room temperature for 50 mil-utes. 1t is then treated with water and 20O ~Cl and the yellow oil extracted with 3 x 150 ml.
of ethyl acetate. The ethyl acetate extract is dried over magnesium sulfate and removed to yield ll.l ~. l-(3-mercapto-2-methylpropanoyl)-DI,-pipecolic acid as a viscous oil. Rf 0.62 [silica gel, benzene, acetic acid (7:2)].
~ =
3-[(4-Methoxyphenyl)methylthio]-2-methylpropanoic acid p-Methoxy-a-toluene thiol (15.4 g., O.l mol.) is added to a solution of methacrylic acid (8.6 g., O.l mol.) in 50 ml. 2N sodium hydroxide. The mixture is heated on the steam bath for three hours, then refluxed for two hours and cooled. The mixture is extrac-ted with ether, then the a~ueous layer is acidified with concentrated HCl and extracted with dichloromethane. The acidic extracts are washed with b ine, dried (MgSO4) and evaporated in vacuo.
The resulting semi-solid is taken up in 50 ml. of dichloro-methane, diluted with 50 ml. hexane, and chilled. 3-[(4-methoxyphenyl)methylthio]-2-methylpropanoic acid is collec-ted as a white crystalline solid, m.p. 74-82 (5.5 g.).
Example l50 l-[3-(4-l~ethoxyphenyl)methylthio]-2-me-thylpropanoyl L-proline tert-butyl ester 3-[(4-methoxyphenyl)methyl-thio]-2-methylpropanoic acid (3.6 g." 0.015 mol.), L-proline tert-butyl ester (2.6 g., 0.015 mol.), and dicyclohexylcarbodiimide (3.l g., _ r, ~) _ .. .. . .
~ 5~ Al35b 0.015 mol.) are dissolvecl in 50 ml. of dichloromethane and stirred tnirty minutes at 0 . Tihe cooling bath is removed and the mi~ture stirred overnight (sixteen hours).
The resulting suspension is ri:ltered and the ~iltrate washed with 5~ potassium bisul~ate, saturated sodium bicarbonate and brine, then dried (MgSO4) and evaporated in vacuo.
The resulting clear oil is applied to a 250 ml. silica gel column and chromatographed using 20% ethyl acetate/
hexane as eluant. The main fraction (~f = 0.70, silica gel, ethyl acetate) is evaporated to 5.5 g. (93~) of 1-[3-t4-methoxyphenyl)methylthio]-2-methylpropanoyl-L-proline tert-butyl ester as a clear oil. Rf = 0.70 (silica gel, ethyl acetate); Rf = 0.60 (silica gel, ether).
Example 151 .-(3-Mercapto-2-methylpropanoyl)-L-proline The ester from ~xample 150 (1.2 g., 0.003 mol.), anisole (5 ml.) and trifluoromethanesulfonic acid (0.5 ml.) are dissolved in 20 ml. of trifluoroacetic acid under nitrogen, and the resulting red solution let stand one hour at room temperature. The solution is evaporated in vacuo to a red residue which is -taken up in ethyl acetate and washed with water, brine, then dried (MgSO4) and evaporated.
The residue is repeatedly triturated with hexane and the residual hexane evaporated; the oil residue amounts to 0.4 g. A portion (180 mg.) of this material is subjected to preparative thin-layer chromatography on 2 mm silica gel plates using benzene/acetic acid 75:25 as eluant. The main nitroprusside-positive band (Rf = 0.~0) is recovered, affording 135 mg. of 1-(3-mercap-to-2-methylpropanoyl)-L-proline as an oil. 'rLC using benzene/acetic acid 75:25
The temperature rises to 29 and a clear solution forms.
Then lO.l g. of N-methylmorpholine is added all at once and the temperature rises to 34 . The mixture is heated on a steam bath for l hour when a clear solution forms.
This is allowed to stand at room temperature overnight and the solid which precipitates is filtered to yield 6.1 g., m.p. 203-204 . The solvent is removed and the viscous residue is triturated with water and 20% HCl. The yellow oil is extracted with 3 x 150 ml. of ethyl acetate.
The ethyl acetate ex-tracts are dried over magnesium sulfate and removed to yield 14 g. of l-[3-(acetylthio)-2-methyl-propanoyl-DL--pipecolic acid as a viscous oil.
Example l~8 l-(3-Mercapto-2-methylpropanoyl)-DL-pipecolic acid Aqueous NE14011 (30 ml. water and 20 ml. conc. NH40H) is stirred under nitrogen at 10 Eor 15 minu-tes. This is -6~--~ ~3~ 5~
~1~135b I
added to 13.0 ~. (0.05 rn) of l-[3-(acetylthio)-2-methylpropanoyl]-DL-pipecolic acid and the resulting solution is stirred for lO minutes under nitrogen; then at room temperature for 50 mil-utes. 1t is then treated with water and 20O ~Cl and the yellow oil extracted with 3 x 150 ml.
of ethyl acetate. The ethyl acetate extract is dried over magnesium sulfate and removed to yield ll.l ~. l-(3-mercapto-2-methylpropanoyl)-DI,-pipecolic acid as a viscous oil. Rf 0.62 [silica gel, benzene, acetic acid (7:2)].
~ =
3-[(4-Methoxyphenyl)methylthio]-2-methylpropanoic acid p-Methoxy-a-toluene thiol (15.4 g., O.l mol.) is added to a solution of methacrylic acid (8.6 g., O.l mol.) in 50 ml. 2N sodium hydroxide. The mixture is heated on the steam bath for three hours, then refluxed for two hours and cooled. The mixture is extrac-ted with ether, then the a~ueous layer is acidified with concentrated HCl and extracted with dichloromethane. The acidic extracts are washed with b ine, dried (MgSO4) and evaporated in vacuo.
The resulting semi-solid is taken up in 50 ml. of dichloro-methane, diluted with 50 ml. hexane, and chilled. 3-[(4-methoxyphenyl)methylthio]-2-methylpropanoic acid is collec-ted as a white crystalline solid, m.p. 74-82 (5.5 g.).
Example l50 l-[3-(4-l~ethoxyphenyl)methylthio]-2-me-thylpropanoyl L-proline tert-butyl ester 3-[(4-methoxyphenyl)methyl-thio]-2-methylpropanoic acid (3.6 g." 0.015 mol.), L-proline tert-butyl ester (2.6 g., 0.015 mol.), and dicyclohexylcarbodiimide (3.l g., _ r, ~) _ .. .. . .
~ 5~ Al35b 0.015 mol.) are dissolvecl in 50 ml. of dichloromethane and stirred tnirty minutes at 0 . Tihe cooling bath is removed and the mi~ture stirred overnight (sixteen hours).
The resulting suspension is ri:ltered and the ~iltrate washed with 5~ potassium bisul~ate, saturated sodium bicarbonate and brine, then dried (MgSO4) and evaporated in vacuo.
The resulting clear oil is applied to a 250 ml. silica gel column and chromatographed using 20% ethyl acetate/
hexane as eluant. The main fraction (~f = 0.70, silica gel, ethyl acetate) is evaporated to 5.5 g. (93~) of 1-[3-t4-methoxyphenyl)methylthio]-2-methylpropanoyl-L-proline tert-butyl ester as a clear oil. Rf = 0.70 (silica gel, ethyl acetate); Rf = 0.60 (silica gel, ether).
Example 151 .-(3-Mercapto-2-methylpropanoyl)-L-proline The ester from ~xample 150 (1.2 g., 0.003 mol.), anisole (5 ml.) and trifluoromethanesulfonic acid (0.5 ml.) are dissolved in 20 ml. of trifluoroacetic acid under nitrogen, and the resulting red solution let stand one hour at room temperature. The solution is evaporated in vacuo to a red residue which is -taken up in ethyl acetate and washed with water, brine, then dried (MgSO4) and evaporated.
The residue is repeatedly triturated with hexane and the residual hexane evaporated; the oil residue amounts to 0.4 g. A portion (180 mg.) of this material is subjected to preparative thin-layer chromatography on 2 mm silica gel plates using benzene/acetic acid 75:25 as eluant. The main nitroprusside-positive band (Rf = 0.~0) is recovered, affording 135 mg. of 1-(3-mercap-to-2-methylpropanoyl)-L-proline as an oil. 'rLC using benzene/acetic acid 75:25
-7()-~ ~r~ ~J~ ~IA135b (Rf = 0.40) and chlorolorm/methanol~acetic acid 50:40:10 (Rf = 0.62).
Example 152 1-(3-Mercapto-2-D-m_thylpropanoyl)-L-proline IJnder a blan~et of argon 1-~3-(acetylthio)-2-~methylpropalloyl]-L-proline (]0.0 g.) is slurried in water (150 ml.) at 10 . To this mixture is added 5N
sodium hydroxide and the pH of the solution maintained at 13 for 1.5 hours. After this time, when the uptake of sodium hydroxide had ceased, the solution is acidi~fied to a pH = 2.0 with concentrated sulfuric acid.
The aqueous solution is then ex-tracted three times with methylene chloride (3 x 150 ml.) and the combined methylene chloride fractions concentrated to an oil. The concentrate is taken up in ethyl acetate, filtered and the filtrate diluted with hexane (30 ml.).
An additional amount of hexane is added after 1/2 hour and then the mixture cooled to 10 for 1 hour.
The crystals are filtered and washed with hexane ~2 x 25 ml.) and dried to constant weight to give 1-(3-mercapto-2-D-methylpropanoyl)-L-proline as white crystals, 6.26 g., m.p. 100-iO2.
Example 153 1-[3-Tosyloxy-2-methylpropanoyl]-L-proline ~y substituting 3-tosyloxy-2-methylpropanoic acid chloride for the 3-acetylthio-2-methylpropanoic acid chloride in the procedure of Example 2~b 1-[3-tosyloxy-2-methylpropanoyl]-L-proline is obtained.
-7~-~ 3.~ 135b . E~~ r~l 1-[3-~cetylthio-2-met~lylpropanoyl1-I.-prolirle 1-[3-Tosyloxy-2-methylpropanoyl]-L-proline (3.5 g.) is added to a solution of thiolacetic acid (1.1~ g.), and triethylamine (3.5 ml.) in ethyl acetate (20 ml.). The solution is maintained at 50 for three hours, cooled, diluted with ethyl acetate (100 ml.), and washed with dilute hydrochloric acid. The organic layer is dried and concentrated to dryness in vacuo. The 1~ residue is dissolved in acetonitrile and dicyclohexylamine is added. The crystalline precipitate is recrystallized from isopropanol to yield l-[3-acetylthio-2-D-methyl-propanoyl)-L-proline, dicyclohexylamine salt, m.p.
187-1~8 , [a]D -67 (c 1,4, EtOH). This salt is converted to the free acid, m.p. 83-85 (an isomorphic form of m.p. 104-lOS is obtained if the crystallizing solution is seeded with high melting material). `
Example 155 1-(3-Mercaptopropanoyl)-L-proline, t-butyl ester To a stirred solution of 1.71 g. (10 mmoles) of proline t-butyl ester and 1.35 g. (10 mmoles) of 1-hydroxybenzotriazole hydrate in 20 ml. of N,N-dimethyl-formamide at 0-5 are added 2.06 g. (10 mmole) of N,N'-dicyclohexylcarbodiimide. The mixture is stirred for 10 minutes, followed by the addition of 1.06 g. (10 mmole) of 3-mercaptopropanoic acid in 2 ml. of N,N-dimethyl-formamide- The mixture is then s-tirred at 0-5 for 1 hour, and at room temperature overnight.
The precipitated N,N'-dicyclohexylurea is filtered off, and -the ~iltrate conccntrated in vacuo.
A1 3 5b The residue is ta~en up in eth~l acetate, washed thoroughly with sa~urated aqueous sodi~lm bicarbonate, dried, and coneentrated in vacuo to 2.5 g. of oil.
The oil is taken up in 1:1 ethyl aceta-te-hexane and applied to a silica gel column (100 g.). ~lution with 1:1 ethyl acetate-hexane affords 1.40 g. (54~) of 1-(3-mercaptopropanoyl)-L-proline, t-butyl ester as an oil, which crystallizes on standing. Recrystallization from ether-hexane yields 0.9 g. of colorless crystalline solid, m.p. 55-60, identical to the compound of Example 17.
Example 156 1-(3-Mereaptopropanoyl)-L-proline A solution of 75 mg. (0.27 mmole) of 1-[3-[[(ethyl-amino)earbonyl~thio]propanoyl]-L-proline in 1 ml. each of eoneentrated ammonium hydroxide and water is allowed to stand at room temperature for 18 hours under argon. The solution is diluted with a small amount of water and extraeted with ether. The aqueous layer is aeidified with eold eoneentrated hydroehlorie aeid and extracted with ethyl acetate. The combined extracts are dried and ;
eoneentrated in vacuo to give a compound identical with the product of Example 18. TLC (silica gel; benzene:acetic aeid 7:3) Rf 0.4.
Example 157 Methacryloyl-L-Proline L-proline (23.0 c3., 0.2 mol.) is dissolved in 100 ml. watex and stirred in an ice bath. Methacryloyl ehloride (1~.6 ml., 0.2 mol.) in 25 ml. of methyl isobutyl ketone is added dropwise ovcr three hours. Sodium hydroxide solution ( 2N) is added simultan~ously, maintaining the p~
o~ the reaction mixture at 7Ø Addition of base is con-tinued for four hours after addition of acid chloride has been completed. The reaction mixture is adjusted ~o pH 5 with concentrated HCl and extracted with ethyl acetate.
The aqueous layer is then acidified to pH 2.5 and extracted thoroughly with ethyl acetate. The acidic extracts are washed with brine and dried (MgSO~). The ethyl acetate solution is treated with dicyclohexylamine (40 ml.) and chilled overnight. The resulting white precipitate is filtered and dried, yielding 29 g. (39%) of white solid, m.p. 202-210. The solid is crystallized from 1.5 liters 3:1 acetonitrile/isopropanol to yield 19.7 g. of metha-cryloyl-L-proline, dicyclohexylamine salt as fine white needles, m.p. 202-210.
The salt is dissolved in water/ethyl acetate and the mixture acidified with concentrated HCl. The result-ing suspension is filtered to remove a fine white preci-pitate which is washed well with ethyl acetate. The fil-trate is saturated with sodium chloride and extractedthoroughly with ethyl acetate. The extracts are washed with brine, dried (MgSO4) and evaporated to a clear oil which solidifies. Crystallization from ethyl acetate/hex-ane yields 7.5 g. ~83~) of methacryloyl-L-proline as a white crystalline solid, m.p. 89-93. An analytical sample is obtained by recrystallization, m.p. 95-98.
Example 158 1-(3-Acetylthio-2-D-meth~lpropanoyl)-L-proLine Methacryloy:L-L-proline (183 mg., 0.0001 mol.) is dissolved in thiolacetic acid (0.5 ml.) and allowed .~ , ., ~l~135b to stand at room telllperat~lro ~or sixteen ho~lrs. The solution is evaporated in vacuo to a yellow residue.
Preparative thin layer chromatocJraplly (silica gel, di-chloromethane,'methanol/acetic acid 90:5:5) allows isolation of a clear oil (2~l0 mg.) as the main fraction. TLC (dichloro-methane/methanol/acetic acid 90:5:5) shows this material to be 1-(3-acetylthio-2-DL-methylpropanoyl)-L-proline corresponding to the product o, Example 29B. Rf = 0.35;
(benzene/acetic acid 75:25) Rf = 0.38.
The oil is dissolved in 3 ml. acetonitrile, treated with dicyclohexylamine until -the solution is basic, and chilled. A white crystalline solid (106 mg.) m.p. 175-181 , is collected. Crystallization from isopropanol gives l-(3-acetylthio-2-D-methylpropanoyl)-L-proline, dicyclohexylamine salt, m.p. 187-188 , identical with this product in Example 29A.
Example 159 _.
l-[Dithiobis-(2-methyl-3-propanoyl)]-bis-L-proline ` -By substituting 3,3'-dithiobis-2-methylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the pro-cedure of Example 29B, l-[dithiobis-(2-methyl-3-propanoyl)]-bis-L-proline is obtained.
Example 160 1-(3-Mercapto-2 - methylpropanoyl)-L-proline Zinc dust (10.0 g.) is added to a slurry of the product of Example 159 (5.0 g.) in 100 ml. of l.O N
sulfuric acid and the mixture is stirred at 18 for four hours under a blanket of nitrogen. The solution is then filtered, the zinc washed with wat~r (~0 ml.) ancl the combitled filtrates are ~xtrac-ted with methylene chloride 5`~
HA135b (3 x 75 ml.). The methylene chloride washes are back extracted with water (25 ml.) and then the or~anic solution concentrated to an oil. This oil is taken up in ethyl acetate (20 ml.) and ~iltered. ~lex~ne (15 ml.) is added to the filtrate and the mixture is stirred for 15 minutes. After this time, an additional volume of he~ane (30 ml.) is added and the solution cooled to 5 for 1 hour. The mixture is then filtered, and the product is washed with hexane (2 x 10 ml.) and dried to give 4.17 g.
of ~hite crystals of the product, 1-(3-mercapto-2-methylpropanoyl)-L-proline. TLC, Rf = 0.60 (Solvent system: benzene/acetic acid 75:25).
Example 161 3-Ben 2yl thio-2-methylpropanoic acid By substituting a--toluenethiol for p-methoxy-a-toluenethiol in the procedure of Example 149, 3-benzylthio-2-methylpropanoic acid is obtained.
Example 162 1-[3-(Benzylthio)-2-methylpropanoyl]-L-proline tert.
butyl ester By sub~tituting 3-benzylthio-2-methylpropanoic acid for the 3-[(4-methoxyphenyl)me-thylthio]-2-methyl-propanoic acid in the procedure of Example 150, 1-[3-(benzylthio)-2-methylpropanoyl]-L-proline tert. butyl ester is obtained.
Example 163 1-[3-(Benzylthio)-2-methylpropanoyl]-L-proline 1-[3-(benzylthio),-2-methylpropanoyl]-L-proline tert. butyl ester (7.8 g.) is dissolved in a mixture of anisole (55 ml.) and trifluoroacetic acid (110 ml.). After .,_ ... . . ~
~A135b one hour storage at room temperature, the solvent is removed in vacuo and the resicluc is dlssolved in ether, washed several times with saturated sodium chloride, dried over magnesium sulfate and evaporated to dryness in vacuo to yield l-[3-(benzylthio)-2-methylpropanoyl~-L-proline.
Rf 0.5 (Silica gel, Benzene/acetic acid 3:1) Rf 0.5.
(Silica gel, Methyl-ethylketorle/acetic acid/pyridine/water 14:1:2:1).
Example 164 1-(3-Mercapto-2-methylpropanoyl)-L-proline 1-[3-(benzylthio)-2-methylpropanoyl]-L-proline (0.1 g.) is suspended in boiling liquid ammonia (10 ml.) and small pieces of sodium are added with stirring un-til persistent blue color. The color is discharged with a few crystals of ammonium sulfate and the ammonia is allowed to evaporate under a current of nitrogen. The residue is dissolved in a mixture of dilu-te hydrochloric acid and ethyl acetate. The organic layer is dried and concentrated to dryness in vacuo to yield l-(3-mercapto-2-methylpropanoyl)-L-proline. Rf: 0.35 (Silica gel; Benzene/acetic acid 3:1), Rf 0.5 (Silica gel; Methyl-ethylketone/acetic acid/
pyridine/water 14:1:2:1) identical to the compound of Example 34.
Example 165 3-Triphenylmethyltllio-2-me-thylpropanoic acid A solution of 3-mercapto-2-methylpropanoic acid (1.2 g.) ancl tritylchloride (2.~ g.) in methylene chloride (50 ml.) is kept at room temperature for 2 hours.
The mixture is warmed in a stcam bath for 20 minutes and then evaporated to dryness in vacuo and the residue is dissolved ~-IA135b in saturated aqueous sodi~l bicarbonate and the solution is washed with ethyl acetate. The aqueous phase is acidified to pH 3 and e~trac-ted with ethyl ace-tate. The organic layer is dried and concentrated to dryness to give 3-triphenylmethylthio-2-methylpropanoic acid. Rf 0.8 (Silica gel, Benzene/acetic acid 3:1).
E~ample 166 1-[3-(Triphenylmethylthio)-2-methylpropanoyl]-L-proline tert.butyl ester By substituting 3-triphenylmethylthio-2-methyl-propanoic acid for the 3-~(4-methoxyphenyl)methylthiol- ;
2-methylpropanoic acid in the procedure of Example 150, 1-[3-(triphenylmethylthio)-2-methylpropanoyl]-L-proline tert.butyl ester is obtained.
Example 167 1-[3-(Triphenylmethylthio)-2-methylpropanoyl]-L-proline 3-Triphenylmethyl-thio-2-methylpropanoic acid (1.8 g.) and N,N'-carbonyldiimidazole (0.8 g.) are dissolved in tetrahydrofuran (10 ml.) with stirring at room temperature. After -twenty minutes, the solution is added to a mixture of L-proline (0.6 g.) and N-methyl-morpholine (1 g.) in dimethylacetamide (20 ml.~. The resulting mixture is stirred overnight at room temperature, çoncentrated to dryness and the residue dissolved in a mixture of e-thyl acetate and 10% aqueous potassium bisulfate.
The organic layer is separated and dried and concentrated ta dryness in vacuo to obtain 1~[3-(triphenylmethylthio)-2-methylpropanoyl]-L-proline. Rf: = 0.4 (~ilica gel, Benzene/acetic acid 3:1), Rf 1.0 (Silica gel, Methyl-ethyl-ketone/acetic acid/pyridine/wa-ter 14:1:2:1).
-7a-.
.
IA l 3 5 b E.~ample 168 1-[3-~lercapto-2-methylpropanoyl)-L-proline 1-[3-(triphenylmethylthio)-2-methylpropanoyl]-L-proline tert.butyl ester (5 g~) is dissolved in a mixture of anisole (55 ml.) and trifluoroacetic acid (110 ml.).
After one hour storage at room temperature, the solvents are remo~ed in vacuo and the residue is applied -to a column of silica gel equilibrated with benzene:acetic acid (75:25) and eluted with the same solvent. The fractions corresponding to the component witll Rf 0.40 tTLC silica gel with same system) are pooled and concentrated to dryness to yield l-[3-mercapto-2-methylpropanoyl)-L-proline. Rf 0.62 (silica gel, chloroform/methanol:
acetic acid:water 50:40:10), identical to the compound of Example 34.
Example 169 3-(Tetrahydropyran-2-ylthio)-2-methylpropanoic acid To a solution of 3-mercapto-2-methylpropanoic acid (2.4 q.) and freshly distillled 2,3-dihydro-4H-pyrane (1.9 g.) in benzene (60 ml.), boron trifluoride etherate (2.8 g.) is added. After two hours, potassium carbonate (4 g.) is added, the mixture is stirred and filtered. The filtrate is concentrated to dryness to yield 3-(tetrahydropyran-2-ylthio)-2-me-thylpropanoic acid.
Example 170 .
1-[3-(Tetrahydropyran-2-ylthio)-2-methylpropanoyl]-L-proline By substi-tuting 3-(tetrahydropyran-2-ylthio)-2-methylpropanoic acid for the 3-triphenylmethylthio-2-methylpropanoic acid in the procedure of Example 167, 1-[3-(tetrahydropyran-2-yl-thio)-2-methylpropanoyl]-L-proline .. . .
~IA 1 3 5 b is obtained. Rf: 0.8 (Silica gel, Benzene/acetic acid 3:1; Rf: 0.75 (Silica gel, l~ethyl-ethylketone/Acetic acid/
pyridine/water; 14:1:2:1).
~ample 17l 1-(3-~lercapto-2-methylpropano~l)-L-proline A solution o~ 1-[3-(tetrahydroPyran-2-yl-thio)-2-methylpropanoyl)-L-proline (1 g.) in a mix-ture oE methanol (25 ml.) and concentrated hyclrochloric acid (25 ml~) is stored at room temperature Eor 30 minutes. The solvents are removed in vacuo to yield 1-(3-mercapto-2-methyl-propanoyl)-L-proline. Rf: 0.35 (silica gel, Benzene/
acetic acid, 3:1), Rf 0.5 (silica gel, Methyl-ethylketone/
acetic acid/pyridine/water 14:1:2:1) identical to the compound of Example 34.
Example 172 .
3-Acetamidomethylthio-2-methylpropanoic acid 3-~lercapto-2-methylpropanoic acid (2.4 g.) and N-hydroxymethylacetamide (1.8 g.) are dissolved in trifluoroacetic acid and the solu-tion is stored at room temperature for one hour. The trifluoroacetic acid is removed in vacuo and the residue is dried in vacuo over potassium hydroxide to yield 3-acetamidomethylthio-2- , methylpropanoic acid.
Example 173 1-[3-(Acetamidomethylthio)-2-methylpropanoyl]-L-proline By substituting 3-acetamidomethylthio-2-methyl-propanoic ac:id for the 3-(tetrahydropyran-2-yl -thio)-2-methylpropanoic acid in the procedure of Example 170 1-[3-(acetamidomethylthio)-2-i --~0--.
IA135b methylpropanoyl]-L-proline is obtained. Rf 0.2 (Silica gel, Benzene/acetic acid 3:1) Rf 0.3 (Silica gel, Methyl-ethylketone~acetic acid/pyridine/water 14:1:2:1).
E~ample 174 1-(3-Mercapto-2-methylpropanoyl)-L-proline 1-[3-(acetamidomethylthio)-2-methylpropanoyl~-L-proline (1.4 g.) and mercuric acetate (1.93 g.) are dissolved in a mixture of acetic acid (25 ml.) and water (25 ml.).
After one hour stirring on the steam bath, hydrogen sulfide is bubbled through until no more precipitation of mercuric sulfide is observed. The mixture is filterd, the precipitate is washed with ethanol, and the filtrate is concentrated to dryness in vacuo to yield l-(3-mercapto-2-methylpropanoyl)-L-proline. Rf: 0.35 (Silica gel, Benzene/Acetic acid 3:1);
Rf : 0.5 (Silica gel, Methyl-ethylketone/Acetic acid/
pyridine/water 14:1:2:1) identical to the compound of Example 34.
Example 17i 1-(3-M_rc_pto-2-methylpropanoyl)-L-proline ter-t. butyl ester To the cold (5 ) solution of 1.2 g. (10 mMol.) of 3_ mercapto-2-methylpropanoic acid and 1.7 g. (10 mMol.) of L-proline tert. butyl ester in 25 ml. dichloromethane 2.26 g. of dicyclohexylcarbodiimide in 5 ml. dichloromethane is added in portions. After 2 hours a-t room temperature, 5 drops of acetic acid are added, the mixture is filtered and the filtrate evaporated to an oily residue. This residue is taken up in 20 ml. of petroleum ether-ethyl acetate (3:1) and applied to a 150 ml. silica gel column prepared in pe-troleum e-ther. The fraction eluted with petroleum ether-ethyl acetate (1:1) contains the product, I '.
IIA135b 1-(3-mercapto-2-methylpropanoyl)-l.-prol,ine tert.butyl ester. I
This fraction (0.6 g.) is dried over P2O5 in vacuo for 12 hours. Rf 0.6 (Silica gel, Benzene~Acetie acid 3:1), Rf 0.8 (Silica gel, Methyl-ethylketone/acetic acid/pyridine/
water 14:1:2:1).
Example 176 1-(3-Mercapto-2-methylpropanoyl)-L-proline By subs-tituting 1-(3-mereapto-2-methylpropanoyl)-L-proline tert. butyl es-ter for the l-(3-mereaptopropanoyl-L-proline tert.butyl ester in the proeedure of Example 18C, 1-(3-mereapto-2-methylpropanoyl)-L-proline is obtained.
Rf 0.35 (Siliea gel, Benzene~aeetie acid 3:1), Rf 0.5 (Siliea gel, Methyl-ethylketone/Aeetie aeid/Pyridine/Water 14:1:2:1), identieal to the eompound of Example 34.
-~2------- -- . _ ' ~'5i~ I-IA135b The raccmic form OL ~he I illal ~lOdUCt ill any of the foregoing examples is produced by utili~ing the DL-form of the starting amino acid instead of the L-form.
Similarly, tile D-form of the final products in any of tne foregoing exarlples is produced by utilizin(3 the D-form o~ tne starting amino acid instead of the L-forn).
Example 177 1000 tablets each containing 100 mg. of 1-(2-mercaptopropanoyl)-L-proline are produced from the following 10 ingredients:
1-(2-Mercaptopropanoyl)-L-proline100 g.
Corn starch 50 g Gelatin 7 5 g, Avicel (microcrystalline cellulosc) ~5 g.
~lagnesi~n stearate 2.5 g.
The 1-(2-mercaptopropanoyl)-L-proline and corn I-starch are admixed with an aqueous solution of the gelatin.
The mixture is dried and ground to a fine powder. The Avicel and then the magnesium stearate are admixed with the granulation. This is then compressed in a table-t to form 1000 tablets each containing 100 mg. of active ingredient.
Example 178 By substituting 100 g. of 1-(3-mercapto-2-D-meth~lpropanoyl)-L-proline for the 1-(2-mercaptopropanoyl)-L-proline in Example 177, 1000 tablets each containing 100 mg. I
of the 1-(3-mercapt:o-2-D-metilylpropanoyl-L-proline are produced.
!
IA135b am~lc 17~
1000 tablets each containlllq 200 mg. of 1-(2-mercaptoacetyl)-L-prollne are produced from the following ingredients:
1-(2-~ercaptoacetyl)-L-proline 200 g.
Lactose 100 g.
Avicel 150 g.
Corn starch 50 c;
Magnesium stearate 5 g.
l'he 1-(2-mercaptoacetyl)-I.-proline, lactose and Avicel are admixed, then blended with the corn starch.
Magnesium stearate is addecl. The dry mixture is compressed in a tablet press to form 1000 505 mg. tablets each containing 200~mg. of active ingredient. The tablets are coated with a solution of Methocel E 15 (methyl cellulose) includincJ as a color a lake containing yellow ~6.
~ample 180 Two piece ~1 gelatin capsules each containing 250 mg.
of l-(2-mercaptopropanoyl)-L-proline are filled with a mixture of the following inyredients:
1-(2-Mercaptopropanoyl)-L-proline 250 mg.
Magnesium stearate 7 my.
USP lactose 193 my.
Example 181 An injectable solution is produced as follows:
1-(2-Mercaptopropanoyl)-L-proline 500 mg. '~
Methyl para~en 5 g, Propyl paraben 1 g.
Sodium chloride 25 g.
Water ~or injectic)~ . 5 1.
_, ~ 3~ 135b Th~- active substance, prescrvatives arld soclium chloride are dissolved in 3 li~ers of ~ater for injection and then the volume i5 brouy}lt Up to 5 liters. '['he solution is filtered through a sterile filter and aseptically filled into presterili~ecl vials ~hlcll are then closed with pre-sterilized rubber closures. F'ach vial contains 5 Inl. of solution in a concentration of 100 mg. of active ingredient per ml. of solution for injection.
E~ample 182 By substituting 100 g. oE 1,1'-[dithiobis(2-V-methyl-3-propanoyl)]-bis-L-proline for the 1-(2-mercaptopropanoyl)-L-proline in Example 177, 1000 tablets each containing 100 my.
of tne l,l'-[dithiobis[2-D-methyl-3-propanoyl)]-bis-L-proline are produced.
Each of the products of the examples can be similarly formulated by substitutiny it for the active inyredient in L~amples 177, 179, 180 or 181.
.~
., ~
,~
Example 152 1-(3-Mercapto-2-D-m_thylpropanoyl)-L-proline IJnder a blan~et of argon 1-~3-(acetylthio)-2-~methylpropalloyl]-L-proline (]0.0 g.) is slurried in water (150 ml.) at 10 . To this mixture is added 5N
sodium hydroxide and the pH of the solution maintained at 13 for 1.5 hours. After this time, when the uptake of sodium hydroxide had ceased, the solution is acidi~fied to a pH = 2.0 with concentrated sulfuric acid.
The aqueous solution is then ex-tracted three times with methylene chloride (3 x 150 ml.) and the combined methylene chloride fractions concentrated to an oil. The concentrate is taken up in ethyl acetate, filtered and the filtrate diluted with hexane (30 ml.).
An additional amount of hexane is added after 1/2 hour and then the mixture cooled to 10 for 1 hour.
The crystals are filtered and washed with hexane ~2 x 25 ml.) and dried to constant weight to give 1-(3-mercapto-2-D-methylpropanoyl)-L-proline as white crystals, 6.26 g., m.p. 100-iO2.
Example 153 1-[3-Tosyloxy-2-methylpropanoyl]-L-proline ~y substituting 3-tosyloxy-2-methylpropanoic acid chloride for the 3-acetylthio-2-methylpropanoic acid chloride in the procedure of Example 2~b 1-[3-tosyloxy-2-methylpropanoyl]-L-proline is obtained.
-7~-~ 3.~ 135b . E~~ r~l 1-[3-~cetylthio-2-met~lylpropanoyl1-I.-prolirle 1-[3-Tosyloxy-2-methylpropanoyl]-L-proline (3.5 g.) is added to a solution of thiolacetic acid (1.1~ g.), and triethylamine (3.5 ml.) in ethyl acetate (20 ml.). The solution is maintained at 50 for three hours, cooled, diluted with ethyl acetate (100 ml.), and washed with dilute hydrochloric acid. The organic layer is dried and concentrated to dryness in vacuo. The 1~ residue is dissolved in acetonitrile and dicyclohexylamine is added. The crystalline precipitate is recrystallized from isopropanol to yield l-[3-acetylthio-2-D-methyl-propanoyl)-L-proline, dicyclohexylamine salt, m.p.
187-1~8 , [a]D -67 (c 1,4, EtOH). This salt is converted to the free acid, m.p. 83-85 (an isomorphic form of m.p. 104-lOS is obtained if the crystallizing solution is seeded with high melting material). `
Example 155 1-(3-Mercaptopropanoyl)-L-proline, t-butyl ester To a stirred solution of 1.71 g. (10 mmoles) of proline t-butyl ester and 1.35 g. (10 mmoles) of 1-hydroxybenzotriazole hydrate in 20 ml. of N,N-dimethyl-formamide at 0-5 are added 2.06 g. (10 mmole) of N,N'-dicyclohexylcarbodiimide. The mixture is stirred for 10 minutes, followed by the addition of 1.06 g. (10 mmole) of 3-mercaptopropanoic acid in 2 ml. of N,N-dimethyl-formamide- The mixture is then s-tirred at 0-5 for 1 hour, and at room temperature overnight.
The precipitated N,N'-dicyclohexylurea is filtered off, and -the ~iltrate conccntrated in vacuo.
A1 3 5b The residue is ta~en up in eth~l acetate, washed thoroughly with sa~urated aqueous sodi~lm bicarbonate, dried, and coneentrated in vacuo to 2.5 g. of oil.
The oil is taken up in 1:1 ethyl aceta-te-hexane and applied to a silica gel column (100 g.). ~lution with 1:1 ethyl acetate-hexane affords 1.40 g. (54~) of 1-(3-mercaptopropanoyl)-L-proline, t-butyl ester as an oil, which crystallizes on standing. Recrystallization from ether-hexane yields 0.9 g. of colorless crystalline solid, m.p. 55-60, identical to the compound of Example 17.
Example 156 1-(3-Mereaptopropanoyl)-L-proline A solution of 75 mg. (0.27 mmole) of 1-[3-[[(ethyl-amino)earbonyl~thio]propanoyl]-L-proline in 1 ml. each of eoneentrated ammonium hydroxide and water is allowed to stand at room temperature for 18 hours under argon. The solution is diluted with a small amount of water and extraeted with ether. The aqueous layer is aeidified with eold eoneentrated hydroehlorie aeid and extracted with ethyl acetate. The combined extracts are dried and ;
eoneentrated in vacuo to give a compound identical with the product of Example 18. TLC (silica gel; benzene:acetic aeid 7:3) Rf 0.4.
Example 157 Methacryloyl-L-Proline L-proline (23.0 c3., 0.2 mol.) is dissolved in 100 ml. watex and stirred in an ice bath. Methacryloyl ehloride (1~.6 ml., 0.2 mol.) in 25 ml. of methyl isobutyl ketone is added dropwise ovcr three hours. Sodium hydroxide solution ( 2N) is added simultan~ously, maintaining the p~
o~ the reaction mixture at 7Ø Addition of base is con-tinued for four hours after addition of acid chloride has been completed. The reaction mixture is adjusted ~o pH 5 with concentrated HCl and extracted with ethyl acetate.
The aqueous layer is then acidified to pH 2.5 and extracted thoroughly with ethyl acetate. The acidic extracts are washed with brine and dried (MgSO~). The ethyl acetate solution is treated with dicyclohexylamine (40 ml.) and chilled overnight. The resulting white precipitate is filtered and dried, yielding 29 g. (39%) of white solid, m.p. 202-210. The solid is crystallized from 1.5 liters 3:1 acetonitrile/isopropanol to yield 19.7 g. of metha-cryloyl-L-proline, dicyclohexylamine salt as fine white needles, m.p. 202-210.
The salt is dissolved in water/ethyl acetate and the mixture acidified with concentrated HCl. The result-ing suspension is filtered to remove a fine white preci-pitate which is washed well with ethyl acetate. The fil-trate is saturated with sodium chloride and extractedthoroughly with ethyl acetate. The extracts are washed with brine, dried (MgSO4) and evaporated to a clear oil which solidifies. Crystallization from ethyl acetate/hex-ane yields 7.5 g. ~83~) of methacryloyl-L-proline as a white crystalline solid, m.p. 89-93. An analytical sample is obtained by recrystallization, m.p. 95-98.
Example 158 1-(3-Acetylthio-2-D-meth~lpropanoyl)-L-proLine Methacryloy:L-L-proline (183 mg., 0.0001 mol.) is dissolved in thiolacetic acid (0.5 ml.) and allowed .~ , ., ~l~135b to stand at room telllperat~lro ~or sixteen ho~lrs. The solution is evaporated in vacuo to a yellow residue.
Preparative thin layer chromatocJraplly (silica gel, di-chloromethane,'methanol/acetic acid 90:5:5) allows isolation of a clear oil (2~l0 mg.) as the main fraction. TLC (dichloro-methane/methanol/acetic acid 90:5:5) shows this material to be 1-(3-acetylthio-2-DL-methylpropanoyl)-L-proline corresponding to the product o, Example 29B. Rf = 0.35;
(benzene/acetic acid 75:25) Rf = 0.38.
The oil is dissolved in 3 ml. acetonitrile, treated with dicyclohexylamine until -the solution is basic, and chilled. A white crystalline solid (106 mg.) m.p. 175-181 , is collected. Crystallization from isopropanol gives l-(3-acetylthio-2-D-methylpropanoyl)-L-proline, dicyclohexylamine salt, m.p. 187-188 , identical with this product in Example 29A.
Example 159 _.
l-[Dithiobis-(2-methyl-3-propanoyl)]-bis-L-proline ` -By substituting 3,3'-dithiobis-2-methylpropanoic acid for the 3-acetylthio-2-methylpropanoic acid in the pro-cedure of Example 29B, l-[dithiobis-(2-methyl-3-propanoyl)]-bis-L-proline is obtained.
Example 160 1-(3-Mercapto-2 - methylpropanoyl)-L-proline Zinc dust (10.0 g.) is added to a slurry of the product of Example 159 (5.0 g.) in 100 ml. of l.O N
sulfuric acid and the mixture is stirred at 18 for four hours under a blanket of nitrogen. The solution is then filtered, the zinc washed with wat~r (~0 ml.) ancl the combitled filtrates are ~xtrac-ted with methylene chloride 5`~
HA135b (3 x 75 ml.). The methylene chloride washes are back extracted with water (25 ml.) and then the or~anic solution concentrated to an oil. This oil is taken up in ethyl acetate (20 ml.) and ~iltered. ~lex~ne (15 ml.) is added to the filtrate and the mixture is stirred for 15 minutes. After this time, an additional volume of he~ane (30 ml.) is added and the solution cooled to 5 for 1 hour. The mixture is then filtered, and the product is washed with hexane (2 x 10 ml.) and dried to give 4.17 g.
of ~hite crystals of the product, 1-(3-mercapto-2-methylpropanoyl)-L-proline. TLC, Rf = 0.60 (Solvent system: benzene/acetic acid 75:25).
Example 161 3-Ben 2yl thio-2-methylpropanoic acid By substituting a--toluenethiol for p-methoxy-a-toluenethiol in the procedure of Example 149, 3-benzylthio-2-methylpropanoic acid is obtained.
Example 162 1-[3-(Benzylthio)-2-methylpropanoyl]-L-proline tert.
butyl ester By sub~tituting 3-benzylthio-2-methylpropanoic acid for the 3-[(4-methoxyphenyl)me-thylthio]-2-methyl-propanoic acid in the procedure of Example 150, 1-[3-(benzylthio)-2-methylpropanoyl]-L-proline tert. butyl ester is obtained.
Example 163 1-[3-(Benzylthio)-2-methylpropanoyl]-L-proline 1-[3-(benzylthio),-2-methylpropanoyl]-L-proline tert. butyl ester (7.8 g.) is dissolved in a mixture of anisole (55 ml.) and trifluoroacetic acid (110 ml.). After .,_ ... . . ~
~A135b one hour storage at room temperature, the solvent is removed in vacuo and the resicluc is dlssolved in ether, washed several times with saturated sodium chloride, dried over magnesium sulfate and evaporated to dryness in vacuo to yield l-[3-(benzylthio)-2-methylpropanoyl~-L-proline.
Rf 0.5 (Silica gel, Benzene/acetic acid 3:1) Rf 0.5.
(Silica gel, Methyl-ethylketorle/acetic acid/pyridine/water 14:1:2:1).
Example 164 1-(3-Mercapto-2-methylpropanoyl)-L-proline 1-[3-(benzylthio)-2-methylpropanoyl]-L-proline (0.1 g.) is suspended in boiling liquid ammonia (10 ml.) and small pieces of sodium are added with stirring un-til persistent blue color. The color is discharged with a few crystals of ammonium sulfate and the ammonia is allowed to evaporate under a current of nitrogen. The residue is dissolved in a mixture of dilu-te hydrochloric acid and ethyl acetate. The organic layer is dried and concentrated to dryness in vacuo to yield l-(3-mercapto-2-methylpropanoyl)-L-proline. Rf: 0.35 (Silica gel; Benzene/acetic acid 3:1), Rf 0.5 (Silica gel; Methyl-ethylketone/acetic acid/
pyridine/water 14:1:2:1) identical to the compound of Example 34.
Example 165 3-Triphenylmethyltllio-2-me-thylpropanoic acid A solution of 3-mercapto-2-methylpropanoic acid (1.2 g.) ancl tritylchloride (2.~ g.) in methylene chloride (50 ml.) is kept at room temperature for 2 hours.
The mixture is warmed in a stcam bath for 20 minutes and then evaporated to dryness in vacuo and the residue is dissolved ~-IA135b in saturated aqueous sodi~l bicarbonate and the solution is washed with ethyl acetate. The aqueous phase is acidified to pH 3 and e~trac-ted with ethyl ace-tate. The organic layer is dried and concentrated to dryness to give 3-triphenylmethylthio-2-methylpropanoic acid. Rf 0.8 (Silica gel, Benzene/acetic acid 3:1).
E~ample 166 1-[3-(Triphenylmethylthio)-2-methylpropanoyl]-L-proline tert.butyl ester By substituting 3-triphenylmethylthio-2-methyl-propanoic acid for the 3-~(4-methoxyphenyl)methylthiol- ;
2-methylpropanoic acid in the procedure of Example 150, 1-[3-(triphenylmethylthio)-2-methylpropanoyl]-L-proline tert.butyl ester is obtained.
Example 167 1-[3-(Triphenylmethylthio)-2-methylpropanoyl]-L-proline 3-Triphenylmethyl-thio-2-methylpropanoic acid (1.8 g.) and N,N'-carbonyldiimidazole (0.8 g.) are dissolved in tetrahydrofuran (10 ml.) with stirring at room temperature. After -twenty minutes, the solution is added to a mixture of L-proline (0.6 g.) and N-methyl-morpholine (1 g.) in dimethylacetamide (20 ml.~. The resulting mixture is stirred overnight at room temperature, çoncentrated to dryness and the residue dissolved in a mixture of e-thyl acetate and 10% aqueous potassium bisulfate.
The organic layer is separated and dried and concentrated ta dryness in vacuo to obtain 1~[3-(triphenylmethylthio)-2-methylpropanoyl]-L-proline. Rf: = 0.4 (~ilica gel, Benzene/acetic acid 3:1), Rf 1.0 (Silica gel, Methyl-ethyl-ketone/acetic acid/pyridine/wa-ter 14:1:2:1).
-7a-.
.
IA l 3 5 b E.~ample 168 1-[3-~lercapto-2-methylpropanoyl)-L-proline 1-[3-(triphenylmethylthio)-2-methylpropanoyl]-L-proline tert.butyl ester (5 g~) is dissolved in a mixture of anisole (55 ml.) and trifluoroacetic acid (110 ml.).
After one hour storage at room temperature, the solvents are remo~ed in vacuo and the residue is applied -to a column of silica gel equilibrated with benzene:acetic acid (75:25) and eluted with the same solvent. The fractions corresponding to the component witll Rf 0.40 tTLC silica gel with same system) are pooled and concentrated to dryness to yield l-[3-mercapto-2-methylpropanoyl)-L-proline. Rf 0.62 (silica gel, chloroform/methanol:
acetic acid:water 50:40:10), identical to the compound of Example 34.
Example 169 3-(Tetrahydropyran-2-ylthio)-2-methylpropanoic acid To a solution of 3-mercapto-2-methylpropanoic acid (2.4 q.) and freshly distillled 2,3-dihydro-4H-pyrane (1.9 g.) in benzene (60 ml.), boron trifluoride etherate (2.8 g.) is added. After two hours, potassium carbonate (4 g.) is added, the mixture is stirred and filtered. The filtrate is concentrated to dryness to yield 3-(tetrahydropyran-2-ylthio)-2-me-thylpropanoic acid.
Example 170 .
1-[3-(Tetrahydropyran-2-ylthio)-2-methylpropanoyl]-L-proline By substi-tuting 3-(tetrahydropyran-2-ylthio)-2-methylpropanoic acid for the 3-triphenylmethylthio-2-methylpropanoic acid in the procedure of Example 167, 1-[3-(tetrahydropyran-2-yl-thio)-2-methylpropanoyl]-L-proline .. . .
~IA 1 3 5 b is obtained. Rf: 0.8 (Silica gel, Benzene/acetic acid 3:1; Rf: 0.75 (Silica gel, l~ethyl-ethylketone/Acetic acid/
pyridine/water; 14:1:2:1).
~ample 17l 1-(3-~lercapto-2-methylpropano~l)-L-proline A solution o~ 1-[3-(tetrahydroPyran-2-yl-thio)-2-methylpropanoyl)-L-proline (1 g.) in a mix-ture oE methanol (25 ml.) and concentrated hyclrochloric acid (25 ml~) is stored at room temperature Eor 30 minutes. The solvents are removed in vacuo to yield 1-(3-mercapto-2-methyl-propanoyl)-L-proline. Rf: 0.35 (silica gel, Benzene/
acetic acid, 3:1), Rf 0.5 (silica gel, Methyl-ethylketone/
acetic acid/pyridine/water 14:1:2:1) identical to the compound of Example 34.
Example 172 .
3-Acetamidomethylthio-2-methylpropanoic acid 3-~lercapto-2-methylpropanoic acid (2.4 g.) and N-hydroxymethylacetamide (1.8 g.) are dissolved in trifluoroacetic acid and the solu-tion is stored at room temperature for one hour. The trifluoroacetic acid is removed in vacuo and the residue is dried in vacuo over potassium hydroxide to yield 3-acetamidomethylthio-2- , methylpropanoic acid.
Example 173 1-[3-(Acetamidomethylthio)-2-methylpropanoyl]-L-proline By substituting 3-acetamidomethylthio-2-methyl-propanoic ac:id for the 3-(tetrahydropyran-2-yl -thio)-2-methylpropanoic acid in the procedure of Example 170 1-[3-(acetamidomethylthio)-2-i --~0--.
IA135b methylpropanoyl]-L-proline is obtained. Rf 0.2 (Silica gel, Benzene/acetic acid 3:1) Rf 0.3 (Silica gel, Methyl-ethylketone~acetic acid/pyridine/water 14:1:2:1).
E~ample 174 1-(3-Mercapto-2-methylpropanoyl)-L-proline 1-[3-(acetamidomethylthio)-2-methylpropanoyl~-L-proline (1.4 g.) and mercuric acetate (1.93 g.) are dissolved in a mixture of acetic acid (25 ml.) and water (25 ml.).
After one hour stirring on the steam bath, hydrogen sulfide is bubbled through until no more precipitation of mercuric sulfide is observed. The mixture is filterd, the precipitate is washed with ethanol, and the filtrate is concentrated to dryness in vacuo to yield l-(3-mercapto-2-methylpropanoyl)-L-proline. Rf: 0.35 (Silica gel, Benzene/Acetic acid 3:1);
Rf : 0.5 (Silica gel, Methyl-ethylketone/Acetic acid/
pyridine/water 14:1:2:1) identical to the compound of Example 34.
Example 17i 1-(3-M_rc_pto-2-methylpropanoyl)-L-proline ter-t. butyl ester To the cold (5 ) solution of 1.2 g. (10 mMol.) of 3_ mercapto-2-methylpropanoic acid and 1.7 g. (10 mMol.) of L-proline tert. butyl ester in 25 ml. dichloromethane 2.26 g. of dicyclohexylcarbodiimide in 5 ml. dichloromethane is added in portions. After 2 hours a-t room temperature, 5 drops of acetic acid are added, the mixture is filtered and the filtrate evaporated to an oily residue. This residue is taken up in 20 ml. of petroleum ether-ethyl acetate (3:1) and applied to a 150 ml. silica gel column prepared in pe-troleum e-ther. The fraction eluted with petroleum ether-ethyl acetate (1:1) contains the product, I '.
IIA135b 1-(3-mercapto-2-methylpropanoyl)-l.-prol,ine tert.butyl ester. I
This fraction (0.6 g.) is dried over P2O5 in vacuo for 12 hours. Rf 0.6 (Silica gel, Benzene~Acetie acid 3:1), Rf 0.8 (Silica gel, Methyl-ethylketone/acetic acid/pyridine/
water 14:1:2:1).
Example 176 1-(3-Mercapto-2-methylpropanoyl)-L-proline By subs-tituting 1-(3-mereapto-2-methylpropanoyl)-L-proline tert. butyl es-ter for the l-(3-mereaptopropanoyl-L-proline tert.butyl ester in the proeedure of Example 18C, 1-(3-mereapto-2-methylpropanoyl)-L-proline is obtained.
Rf 0.35 (Siliea gel, Benzene~aeetie acid 3:1), Rf 0.5 (Siliea gel, Methyl-ethylketone/Aeetie aeid/Pyridine/Water 14:1:2:1), identieal to the eompound of Example 34.
-~2------- -- . _ ' ~'5i~ I-IA135b The raccmic form OL ~he I illal ~lOdUCt ill any of the foregoing examples is produced by utili~ing the DL-form of the starting amino acid instead of the L-form.
Similarly, tile D-form of the final products in any of tne foregoing exarlples is produced by utilizin(3 the D-form o~ tne starting amino acid instead of the L-forn).
Example 177 1000 tablets each containing 100 mg. of 1-(2-mercaptopropanoyl)-L-proline are produced from the following 10 ingredients:
1-(2-Mercaptopropanoyl)-L-proline100 g.
Corn starch 50 g Gelatin 7 5 g, Avicel (microcrystalline cellulosc) ~5 g.
~lagnesi~n stearate 2.5 g.
The 1-(2-mercaptopropanoyl)-L-proline and corn I-starch are admixed with an aqueous solution of the gelatin.
The mixture is dried and ground to a fine powder. The Avicel and then the magnesium stearate are admixed with the granulation. This is then compressed in a table-t to form 1000 tablets each containing 100 mg. of active ingredient.
Example 178 By substituting 100 g. of 1-(3-mercapto-2-D-meth~lpropanoyl)-L-proline for the 1-(2-mercaptopropanoyl)-L-proline in Example 177, 1000 tablets each containing 100 mg. I
of the 1-(3-mercapt:o-2-D-metilylpropanoyl-L-proline are produced.
!
IA135b am~lc 17~
1000 tablets each containlllq 200 mg. of 1-(2-mercaptoacetyl)-L-prollne are produced from the following ingredients:
1-(2-~ercaptoacetyl)-L-proline 200 g.
Lactose 100 g.
Avicel 150 g.
Corn starch 50 c;
Magnesium stearate 5 g.
l'he 1-(2-mercaptoacetyl)-I.-proline, lactose and Avicel are admixed, then blended with the corn starch.
Magnesium stearate is addecl. The dry mixture is compressed in a tablet press to form 1000 505 mg. tablets each containing 200~mg. of active ingredient. The tablets are coated with a solution of Methocel E 15 (methyl cellulose) includincJ as a color a lake containing yellow ~6.
~ample 180 Two piece ~1 gelatin capsules each containing 250 mg.
of l-(2-mercaptopropanoyl)-L-proline are filled with a mixture of the following inyredients:
1-(2-Mercaptopropanoyl)-L-proline 250 mg.
Magnesium stearate 7 my.
USP lactose 193 my.
Example 181 An injectable solution is produced as follows:
1-(2-Mercaptopropanoyl)-L-proline 500 mg. '~
Methyl para~en 5 g, Propyl paraben 1 g.
Sodium chloride 25 g.
Water ~or injectic)~ . 5 1.
_, ~ 3~ 135b Th~- active substance, prescrvatives arld soclium chloride are dissolved in 3 li~ers of ~ater for injection and then the volume i5 brouy}lt Up to 5 liters. '['he solution is filtered through a sterile filter and aseptically filled into presterili~ecl vials ~hlcll are then closed with pre-sterilized rubber closures. F'ach vial contains 5 Inl. of solution in a concentration of 100 mg. of active ingredient per ml. of solution for injection.
E~ample 182 By substituting 100 g. oE 1,1'-[dithiobis(2-V-methyl-3-propanoyl)]-bis-L-proline for the 1-(2-mercaptopropanoyl)-L-proline in Example 177, 1000 tablets each containing 100 my.
of tne l,l'-[dithiobis[2-D-methyl-3-propanoyl)]-bis-L-proline are produced.
Each of the products of the examples can be similarly formulated by substitutiny it for the active inyredient in L~amples 177, 179, 180 or 181.
.~
., ~
,~
Claims (14)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing a compound of the formula wherein R is hydroxy, NH2 or lower alkoxy; R1 and R4 each is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl; R2 is hydrogen, lower alkyl, phenyl, substituted phenyl wherein the phenyl substituent is halo, lower alkyl or lower alkoxy, phenyl-lower alkyl, diphenyl-lower alkyl, triphenyl-lower alkyl, lower alkylthiomethyl, phenyl-lower alkylthiomethyl, lower alkanoylamidomethyl, R5-C-?, R5-M-?, R5-NH-?- or R6-S-R3 is hydrogen, hydroxy or lower alkyl; R5 is lower alkyl, phenyl or phenyl-lower alkyl; R6 is lower alkyl, phenyl, substituted phenyl, wherein the phenyl substituent is halo, lower alkyl or lower alkoxy, hydroxy-lower alkyl or amino-(carboxy)lower alkyl; M is O or S; m is 1, 2 or 3; p is 0, 1 or 2; and basic salts thereof, characterized by acylating a compound of the formula with an acid of the formula and the resulting product is subjected to an addition reaction with the anion or a thiol or thioacid of the formula R2---SH.
2. A process according to claim 1 wherein a proline compound of the formula is acylated with an acid of the formula and the resulting product is subjected to an addition reaction with the anion of a thiol or thioacid of the formula R2SH to form a product of the formula
3. A process according to claim 1 wherein a proline compound of the formula in the L-form is acylated with an acid of the formula and the resulting product is subjected to an addition reaction with the anion of a thiol or thioacid of the formula R2SH to form a product of the formula wherein the proline moeity is in the L-form.
4. A process according to claim 1 wherein a compound of the formula in the L-form is acylated with an acid of the formula and the resulting product is subjected to an addition reaction with the anion of a thioacid of the formula R5COSH to form a product of the formula wherein the proline moiety is in the L-form.
5. A process according to claim 1 wherein a compound of the formula in the L-form is acylated with an acid of the formula wherein R1 is C1-C4 alkyl and the resulting product is subjected to an addition reaction with the anion of a thioacid of the formula R5COSH to form a product of the formula wherein R1 is C1-C4 alkyl and the proline moiety is in the L-form.
6. A process according to claim 1 wherein L-proline is reacted with methacryloyl chloride and then with thiolacetic acid to form 1-(3-acetylthio-2-methylpropanoyl)-L-proline.
7. A process according to claim 1 wherein L-proline is reacted with methacryloyl chloride and then with thiobenzoic acid to form 1-(3-benzoylthio-2-methylpropanoyl)-L-proline.
8. A compound of the formula wherein R is hydroxy, NH2 or lower alkoxy; R1 and R4 each is hydrogen, lower alkyl, phenyl or phenyl-lower alkyl; R2 is hydrogen, lower alkyl, phenyl, substituted phenyl wherein the phenyl substituent is halo, lower alkyl or lower alkoxy, phenyl-lower alkyl, diphenyl-lower alkyl, triphenyl-lower alkyl, lower alkylthiomethyl, phenyl-lower alkylthiomethyl, lower alkanoylamidomethyl, , , , or R6-S-; R3 is hydrogen, hydroxy or lower alkyl; R5 is lower alkyl, phenyl or phenyl-lower alkyl; R6 is lower alkyl, phenyl, substituted phenyl, wherein the phenyl substituent is halo, lower alkyl or lower alkoxy, hydroxy-lower alkyl or amino-(carboxy)lower alkyl; M is O or S; m is 1, 2 or 3; p is 0, 1 or 2; and basic salts thereof, whenever prepared by the process of claim 1.
9. A compound as in claim 8 having the formula whenever prepared by the process of claim 2.
10. A compound as in claim 8 having the formula wherein the proline moiety is in the L-form, whenever prepared by the process of claim 3.
11. A compound as in claim 8 having the formula wherein the proline moiety is in the L-form, whenever prepared by the process of claim 4.
12. A compound as in claim 8 having the formula wherein R1 is C1-C4 alkyl and the proline moiety is in the L-form, whenever prepared by the process of claim 5.
13. A compound as in claim 8 having the name 1-(3-acetylthio-2-methylpropanoyl)-L-proline, whenever prepared by the process of claim 6.
14. A compound as in claim 8 having the name 1-(3-benzoylthio-2-methylpropanoyl)-L-proline, whenever prepared by the process of claim 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA349,475A CA1103256A (en) | 1976-02-13 | 1980-04-09 | Proline derivatives and related compounds |
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US657,792 | 1976-02-13 | ||
| US05/657,792 US4046889A (en) | 1976-02-13 | 1976-02-13 | Azetidine-2-carboxylic acid derivatives |
| US69843276A | 1976-06-21 | 1976-06-21 | |
| US698,432 | 1976-06-21 | ||
| US05/751,851 US4105776A (en) | 1976-06-21 | 1976-12-22 | Proline derivatives and related compounds |
| US751,851 | 1976-12-22 | ||
| CA270,184A CA1101864A (en) | 1976-02-13 | 1977-01-21 | Proline derivatives and related compounds |
| CA349,475A CA1103256A (en) | 1976-02-13 | 1980-04-09 | Proline derivatives and related compounds |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1103256A true CA1103256A (en) | 1981-06-16 |
Family
ID=27508081
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA349,475A Expired CA1103256A (en) | 1976-02-13 | 1980-04-09 | Proline derivatives and related compounds |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1103256A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7056935B2 (en) | 1995-06-07 | 2006-06-06 | Gpi Nil Holdings, Inc. | Rotamase enzyme activity inhibitors |
| US8653131B2 (en) | 2008-08-22 | 2014-02-18 | Baxter Healthcare S.A. | Polymeric benzyl carbonate-derivatives |
-
1980
- 1980-04-09 CA CA349,475A patent/CA1103256A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7056935B2 (en) | 1995-06-07 | 2006-06-06 | Gpi Nil Holdings, Inc. | Rotamase enzyme activity inhibitors |
| US8653131B2 (en) | 2008-08-22 | 2014-02-18 | Baxter Healthcare S.A. | Polymeric benzyl carbonate-derivatives |
| US8962549B2 (en) | 2008-08-22 | 2015-02-24 | Baxter International Inc. | Polymeric benzyl carbonate-derivatives |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 19980616 |