NZ201001A

NZ201001A - Substituted dipeptide derivatives and method of preparation

Info

Publication number: NZ201001A
Application number: NZ20100182A
Authority: NZ
Inventors: J G Berger; J Weinstein
Original assignee: Schering Corp
Priority date: 1982-06-17
Filing date: 1982-06-17
Publication date: 1986-02-21
Also published as: JPS5931744A; JPH0322870B2

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £01 001 20100 1 No.: Date: Priority Date(s): Complete Specification Filed: Class: £:7.'Trr.'.TVT'.f Qtmsios... Publication Dale: fJ;P. J?.®.®.... P.O. Journal, No: jQSP. NO DRAWINGS NEW ZEALAND PATENTS ACT, 195: COMPLETE SPECIFICATION J. P. & s. "■U-& , A "SUBSTITUTED DIPEPTIDES, PROCESSES FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM AND THEIR USE IN THE INHIBITION OF ENKEPHALINASE" CO-RTCKfiTlOfJ X/We, SCHERING CORP I RAT I ON-, of 2000 Galloping Hill Road, Kenilworth, New Jersey 07 033, United States of America, a Corporation organised under and by virtue of the laws of the State of New Jersey, United States of America, hereby declare the invention for which £x/ we pray that a patent may be granted to^BiK/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page la) 2 010 0 SUBSTITUTED DIPEPTIDES, PROCESSES FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM AND THEIR USE IN THE INHIBITION OF ENKEPHALINASE. This invention relates to certain novel substituted dipeptides and processes for their preparation. The invention also relates to pharmaceutical compositions containing substituted dipeptides including novel dipeptides in accordance with this invention. A natural opiate receptor agonist, known as. "enkephalin", which is believed to be a mixture of two peptides H-Tyr-Gly-Gly-Phe-Met-OH.(methionine-enkephalin), and H-Tyr-Gly-Gly-Phe-Len-OH (leucine-enkephalin)both being subsumed hereinafter under the generic name "enkephalin", has been reported to produce a profound analgesia in rats, when injected into the brain ventricles thereof, (Beluzzic et al Nature 260, 625 (1976) ) _ - 2 - 20100 It is known that enkephalin, naturally produced in the body of warm-blooded animals is inactivated by enzymes of the group known as enkephalinases which are also naturally produced in such bodies. It is therefore, of interest to find compounds capable of inhibiting or mitigating the above-mentioned inactivating effect of the enkephalinases. One aspect of the present invention provides substituted dipeptides of the formula: ?3 ?5 ?6 ?7 R. HC N X CON CH-{C) R„ 1 i i y 9 R2 Ks ana the pharmaceutically acceptable salts thereof, in which R1 -is hydrogen; elkyl; halogen- low era Iky 1 ; hydroxy-lower-c 1 kyl ; 1 owere lkoxy-1 over elkyl aryl oxy-lowerelkyl; amino-loweralkyl ; 1 owera lkylamino-loweralkyl; di-loweralkyl aminoloweralkyl; acylamino-loweralkyl; diarylarainoloweralkyl ; ary lamino — loweralkyl ; guanidino loweralkyl;' heteroaryl; aryl; aralkyl; mer-cspto-1oweralkyl ; arylthio-loweralkyl; loweralkylaralkyl; alkylthic- loweralkyl; aralkyloxyalkyl; aralkylthio-alkyl ; or heteroaryloxvaIkyl; wherein the latter 3 radicals may be substituted with halogen, loweralkyl, loweralkoxy, hydroxy, amino, aminoxoethyl, carboxyl, cyano and/or sul-famovl; or alkenyl substituted by a heterocyclic group or alkyl substituted by a heterocyclic group, the latter two heterocyclic groups optionally being substituted by one or more groups chosen from loweralkyl, hydroxy, loweralkoxy, amino, loweralkylamino, di-loweralkyl amino , acyl amino, halogeno, halooenoloweralkyl, cyeno and/or sulfonamide; 20100 1 3 - &2 is -COOH, COO.(loweralkyl), -Coo-(aryl-loweralkyl), -Coo(aryl) o Ron ii / 20 R -COO-CH -0-c-]ower alkyl, -CONx wherein R2Q R2 1 R^^ ere the same or different end are selected from hydrogen, loweralkyl, aryl, aralkyl, or R2Q and R^ taken together form a saturated 5-7 membered ring which can also contain oxygen as a ring heteroatorr^ or the group 0 f ORI0 wherein R11 10 is hydrogen, lower-alkyl or benzyl; and ^11 is hydroxy, alkoxy, benzyloxy, loweralkyl, aryl or-benzyl ; R^ is hydrogen cr loweralkyl; R. (CH ) R | 4 | 2 q A X is -CH- or -N- wherein q is 0 or 1; R is chosen from the oroups defined for R , A ~ inaolvl (e.g. 3-inaolyl), indolylalkyl, (e.g. 3-indolylalkyl) , aminomethyl-phenylloweralkyl, 3-"thianaphthenyljoethy 1 and tetrahydronaphthyl methyl, R -is. hydrogen or loweralkyl, •y.'.is zero .or ;an integer ^frora 1 to 3; R^, R^ and R^ axe chosen from the groups defined for V Rg is chosen from the groups defined for R, and when y is 2 or 3, R^ and Rg can be on the same or different carbon atom. - 4 - 2 010 0 1 R I ^ suoject to the proviso that when X is -CB-,y=0, and R is not O—^-^en °ne or more of the following conditions R n n 11 applies: s) R^ is pyridyl, thienyl, furanyl , naphthyl lower alkyl, naphthyl or aralkylthio; b) R^ is Jowerc]);y] ; c) is furanomethyl, cyclo lower alkyl, aryl lower alkyl, thienylmethyl, tetrahydronaphthyl-methyl; 1- or 2-naphthyl-methyl, 3-thianaphthenyl-methyl, cycloloweralkylmethyl, loweralkoxylower-alkyl, aralkoxy loweralkyl, aryl, substituted aryl in which the substituents are one or more of: halogen, loweralkyl, hydroxyl, loweralkoxy, haloloweralkyl, nitro, mono-or diloweralkylamino, or cyano, and substituted aryl methyl substituted on the aryl moiety, by one or more of the aryl substituents defined in this proviso with the exception of hydroxyl; a) R is acylaniinoloweralkyl, mono-or di-loweralkylamino loweralkyl or one of the groups mentioned above (in (c)j for excluding phenyl. 20 fOO1 - 5 - A most preferred sub-clan of compounds is that in which I4 X is - CH and is hydrogen, substituted or,unsubstituted aryl, heteroaryl where the heteroatom is 0, S, or N, ana substituted or unsubstituted "lower-alky! wherein the substituents on the substituted lower — alkyl are selected from halogen one or more of substituted or unsubstituted aryl, heteroaryl where the heteroatom is 0, S, or N, substituted or unsubstituted arylthio, amino, 1owera1kanoy1 - ami no , mono and di-lower alkyl-emino, substituted or unsubstituted aryloxy, snd substituted or unsubstituted aralkyl thio; in -which the substituents on the substituted aryl groups or moieties are selected from one or more of: halogen, loweralkyl, hydroxyl, 1 owera 1koxy1 , polyhalo-loweralkyl, nitro, mono—or oiloweralkylamino, or cyano; R_ is 0=P-0R._ carboxyl, -COO loweralkyl, -COO-aryl, -COO-aralkyl 2. j 1U Rn wherein the aryl or aryl moiety of the aralkyl group can be 0 n substituted as in R.. , -COO- CH„ -0 - C - loweralkyl, -R20 -CON wherein R21 6 2 0 10 0 1 R2Q and P'22 are the same or different and are selected from hydrogen, loweralkyl, unsubstituted or substituted aryl wherein in the substituents are as defined in in respect of this sub-class of compounds, unsubstituted or substituted aralkyl wherein the substituents are on the aryl moiety and are as defined in R in respect of this sub-class of compounds; or R2Q and R21 together with the nitrogen form a 5-7 membered staturated ring which can also contain oxygen as part of the ring; is hydrogen, furanomethyl, thi enyl methyl , tetrahydronaphthyl methyl , 1- or 2-naphthylmethyl, 3-thi a-naphthenylmethyl, loweralkyl, c y c1o1o we r a 1 k y 1 , cyclo-loweralkylmethyl, hydroxy'loweralkyl, acyl ami no-low er-alkyl, ami no - 1owera 1ky1, mono- or di- 1owera 1ky1 ami no -loweralkyl, 1 ower a 1 k oxy 1 ower a 1 ky 1 , a r a 1 koxy3-ov,,er_ alkyl wherein the aryl moiety can be substituted as defined in in respect of this sub-class of compounds, 3-indolylloweralkyl, aralkyl e.g. benzyl, aryl e.g. phenyl, substituted -arylalkyl e.g. substituted benzyl and substituted aryl e.g. substituted phenyl wherein substituents are as defined for aryl substituents in R^ in respect of this sub-class of compounds; Rg, R^ and Rg are chosen from the groups defined above for R^, y is 0 or 1 to 3 and when y is 2 or 3 R^ and Rg can be on the same or different carbon atoms; and Rg is chosen from the groups defined above for ; and a pharmaceutically acceptable salt thereof. 2 010 0 1 - 7 - Another preferred sub-clan of compounds is that in which y is 1 , 2 or 3, E is aryl J owera 1 ~.y 1 , R^ is carboxyl, -COO- 3 ower a 1 ky 1 , or -COO-arylloweralkyl, R^ is hydrogen, R^ is benzyl, 1-or 2-naphthylinethyl , loweralkyl, substituted or unsubstituted phenyl-1oweralkyl or 2- or 3- thienylmethyl,R, R^, R_ eno R0 are hyorooen, R is carboxyl, or 7 8 y R 20 -CON in which one of R and R \ 20 -21 R 21 is hydrogen ana the other is loweralkyl, or together with the nitrogen atom to which they are attached R and R ^ form a 5-7 membered saturated ring containing oxyten as a ring heteroatore; or a pharmaceutically acceptable salt thereof. Yet another preferred sub-clan of compounds is that wherein y is 1, is 1-naphthylmethyl, para tolyraethyl benzyl or phenylethyl, R2 is carboxy, and R4 is para tolymethyl or benzyl, or a pharmaceutically acceptable salt thereof. The currently most preferred compounds are: (L)-N-(l-carboxy-3-phenylpropyl)-(L)-phenylalanyl-)3-alani ne , or (L)-N-(l - carboxy-2-phenylethyl)-(L)-phenylalanyl-$-alani ne. 2 010 0 1 Another sub-class of compounds of interest is that in I 4 CH0 ' vhich X is -N- , y is preferably zero, R^ is as defined above with reference to formula I, with the possible exception of alkenyl substituted by a heterocyclic group ana "alkyl- substituted by a substituted heterocyclic group ; is -COO (aryl)—COO (aralkyl) or preferably -COOH or —COO(loweralkyl); R^ is hydrogen or loweralkyl; R^ is preferably one of the groups defined for R^ in this §roup of -compounds or (CH_) CH(CH„) in which n is 0 or 1 to 8 and m m 2 n is 2 to 8, adamantyl or indolyl; R,- is hydrogen; Rg is preferably one of the groups defined for R^ in this group of compounds, and Rg is preferably carboxyl. 201001 Yet another sub-class of compounds of interest is that in which R is 0=P — OR, _ jL | J. U Rn , y is preferably zero 1) R^ is as defined above with reference.to formula I with the possible "exception of alkenyl substituted by a heterocyclic group and alkyl substituted by a substituted heterocyclic group ; r* - 74 X is —CH— or —N— R3' R4' R6' R1 0 and R11 are as defined above with reference to formula I; Rg is hydrogen \ Rg is carboxyl and wherein, when R^ is hydrogen, aryl ?4 or heteroaryl X is preferably -CH-. The terras alkyl, alkoxy and alkenyl signify such groups having from 1 to 20 carbon atoms and include such groups which are straight chained, or branched chained and/or comprise one or more alicyclic rings; 2) 3) -JUL 1985 VjP E 1.1 The terms lower alkyl arid lower alkoxy signify such groups having 1 to■8 carbon atoms; The term lower alkenyl signifies such groups having 2 to 8 carbon atoms; The. term aralkyl signifies such groups having 7 to 20 carbon atoms in which the alkyl moiety may be straight chained or branched chained and/or comprise one or more alicyclic rings; 201001 10 - 5) Heterocyclic - embraces . groups having a 4,5 or 6 member ring in which two of the members may be hetero atoms, one of which is nitrogen and the - bther is oxygen or sulfur; { Heteroaryl — embraces 5 or 6 member aromatic rings I having 1 or 2 hetero atoms chosen from S, N and O. i Heteroaralkyl — signifies alkyl groups as defined above substituted by heteroaryl as defined above; 8) Aryl - denotes a radical derived from an aromatic hydrocarbon by the removal of one hydrogen'atom^and embraces phenyl, tolyl and- naphthyl, and substituted phenyl wherein the substitufents are preferably chosen from halogen, hydroxy, polyhaloloweralkyl e.g. trifluoroTethyl, nitro, loweralkoxyamino, loweralkylamino, di-loweralkylamino, acylaraino, loweralkyl, loweralkoxv, amino, cyano and/or sulfanamido. Representative of such novel compounds are the following 2 010 0 1 - li - N- (L-l-carboxy-3-phenylpropyl)-L-3-(3-thienyl)alanyl-L-alanine m.p. 192.5°C - 193°C; N-(D,L-l-carboxy-3-phenylpropyl)-L-3-(2-naphthyl)alanyl-L- alanine m.p. 149°C - 155°C; N- (L-l-ethoxycarbonyl-3-phenylpropyl)-L-3-(21-thienyl)-alanyl-L-alanine, or the maleate salt thereof m.p- 124°C - 124.5°C (100-110°C); N-(D-l-carboxy-3-phenylpropyl)-L-(4-fluorophenyl)alanyl-L-alanine m.p. 147°C - 152°C; N-(L-l-carboxy-3-phenylpropyl)-L-3-(1-naphthyl)alanyl-^alanine, N- (D-l-carboxy-3-phenylpropyl(-L-3-(3-thienyl)alanyl-L-alanine m.p. 163°C - 164°C; N-(L-l-carboxy-3-phenylpropyl)-L-3-(1-naphthyl)alanyl-L-alanine m.p. 155°C - 156°C; N-(l-carboxy-3-phenylpropyl)-L-3-(3-thienyl)alanyl-L-alanine and the monoethanolate thereof m.p. 163°C-164°C; N-(L-(l-carboxy-2-benzylthio)ethyl)-phenylalanyl-(L)-alanine and the sesequihydrate thereof m.p. 153°C - 154°C. (L-l - car boxy- 2- (benzylthi o) -ethyl) —L-phenyl alanyl —J3 — alanine/ K- (L-l-carboxy-2—phenethyl) -L-phenyle 1 anyl- £ — aminobutyr i c- acid m.p. 209°C.-211 C. (179-181°C) K- (L-'l- car boxy- 3-phenyl propyl) —L—phenyl alanyl— £t>- a 1 an in e 189-191^0 or the hemihydrate m.p. 176°C - 190°C. K- (L-l-carbo>:y-3-phenylpr opyl) —D, L- 3 — (1—naphthyl ) al anvl-L-cianine m.p.. 186 C.-194 C. (D) -N- (1-ethoxy car bony 1-3-phenylpropyl) — phenyl al anyl - ^—alanine (N.P. 101-103°C) or the maleate salt thereof, M.P. 94_97°c 2 010 0 - 12 - (D) -N- (l-carboxy_3-phenylpropyl) -phenylalanyl-/3-alanine -M.P. 183-185°C (190-19 2°C) N-L- (l-carboxy-3-phenylpropyl) -l - 3- ( 2-naphthyl) alanyl -L-alanine m.p. 149-155°C. N- [(L)-l -carboxy-2- (1-naphthyl) ethylj - ( l) - ( 4-phenyl -2-amino-butyroyl)-^-alanine, m.p. 206-207°C. N- (L) - (l-carboxy-2-phenylethyl) - (L) -hcmophenyl alanyl -^-alanine, m.p. 200-201°C. N- (L) - (l-ethoxycarbonyl-3-pIjenylpropyl) — (D) -phenylalanyl-f-alanine m.p. 103-105°C. N- (L) - (1-carboxy-2-pheny lethyl) - (L) -phenylalanyl-(^-alanine-2-phenethylamide m.p. 204-205°C. N- (L) _ (l_benzyloxycarbonyl-2-phenylethyl) - ) -phenylalanyl-/^-alanine benzylester, N- (L) - (1-benzyloxycarbonyl-2-phenylethyl)-(L) -phenylalanyl-(^-alanine- ( 2-methyl-3-trif luoromethyl) -anilide m.p.114-116 N- [(D, L) —1—carboxy-2-phenylethylj -L-"leucyl- (L) —phenylalanine or the hemihydrate thereof m.p. 178-180°C. N- £(L) -l-carboxy-2-phenylethylj - (L) -leucyl-[5-alanine trifluoroacetate m.p. 70-72°C. 2 010 0 1 - 13 - N- (L)— (l-carboxy-2-phenylethyl) - (L) -phenylalanyl—(2—alanine-( 2-methyl-3-trifluoromethyl )-anilide m.p. 191-192°C. N-(L)- (l-benzyloxycarbonyl-2-phenylethyl)-(L) -phenylalanyl— ^-alanyl morpholine amide N- [(L)-l-carboxy-2-phenylethylj-(L)-phenylalanyl-p-alanyl-morpholine amide m.p. 127-125°C. N- (L-l-ethoxvcarbonylethyl) -L-2-thienyl—alanylglycine, N- (L-l-ethoxycarbonylethyl) -L-2—thienylalanyl-L—alanine, N- (L-l-ethoxycarbonylethyl) -L-3-thienylalanyl-L—alanine, N- (L-l-ethoxycarbonylethyl) -L-3—thienylalanylglycine, N- (L-l-carboxyethyl) -L-2-thienylalanyl-L-alanine' N- (L-l-tert—butoxycarbonylethyl)-L-2-thienylalanyl-L-alanine < N- ( (R)-l-benzyloxycarbonyl-2-phenylethyl)-(R)-phenylalanyl-ft -alanyl- 2,2-dimethyl propionyloxy methyl ester, N- (l-carboxy-2 (1-naphthylmethyl) ) - (R) -phenylalanyl-j) -alanine m.p. 183-187°C, N-(S)-(l-carboxy-2-phenylethyl)-(S)-paraphenylalanyl-P -alanine, N-(L)-1-carboxy-2-para-methy1-phenylethyl-(L)-phenylalanyl-/? -alanine m.p. 222-2 2 4°C, and the pharmaceutically acceptable salts thereof. 2 010 0 1 - 14 - Among the compounds of formula I in which X is I4 CH I L -N- and is carboxy or -COO(1oweralkyl), Rj. is hydrogen Rg is carboxyl and y is preferably zero, which are of interest are e.g. those in which and R^ are both hydrogen and R^ is -COO (loweralkyl)e.g. -COOC^H^; also those compounds in which R^ is hydrogen, alkyl or aralkyl, R^ is 3-indolyl, aryl or heteroaryl, Rg is hydrogen or loweralkyl, and R^ is hydrogen or loweralkyl; also those compounds in which R^ is aralkyl e.g. C^H,--(Cf^) 2~ ' R^ is carboxy, R^ is aryl e.g. pheny^ and R^ and Rg are both hydrogen; also those compounds in which R^ is alkyl e.g. methyl, R^ is carboxy, R^ is hydrogen, is heteroary Rg is loweralkyl e.g. methyl. R^ is heteroaryl e.g. 4-imidazolyl, and # 2 010 0 1 1 5 -2 5 and those in which R^ is methyl, phenethyl or aralkthioalkyl, R2 is -COOH, R. is phenyl and 4 R g is hydrogen, .methyl or isobutyl; and 30 those corapounds in which R^ is phenethyl or methyl, R^ is -COO(loweralkyl), R^ is hydrogen, R^ is 3-indolyl, heteroaryl or aryl, and R^ is hydrogen or lower alkyl ; Representative examples of such corapounds are those having the following combinations of substituents: (i) R^= hydrogen, . 5 R2= -COOC2H5, R3= H, R^= 3-indolyl, R = H; and (ii) methyl. I O r2= -COOH, R3= H R,= 4-±midazolyl Rfi~ methyl. Among the corapounds of formula I in which R is 0=P OR n 2. * x u ' - 16 2 010 0 1 Rg is carboxyl and y is preferably zero, R/. I which are generally of interest when X is -CH- are those in which R^ is hydrogen, alkyl, aryl or aralkyl and R^ is lower alkyl, aryl , aralkyl (e.g. benzyl), heteroalkyl or heteroaryl, for instance such compounds in which is methyl or phenethyl, R^ and R^ are hydrogen; Rg is hydrogen or lower alkyl (e.g methyl), R^ is hydrogen and R^ is hydroxy or methoxy; and those which are generally of interest when |4 X is -N- are those in which R^ is hydrogen, alkyl, aryl and aralkyl and R^ is lower alkyl, aralkyl e.g. benzyl or heteroaralky1, for instance such compounds in which R^ is methyl or phenethyl, R^s R^, and Rg are hydrogen or 1 owr alkyl e.g. methyl and R^Q is hydrogen and R^ is hydroxy or methoxy. Another group of compounds of particular interest comprises compounds in which is substituted benzyl or phenethyl, R^ is naphthylmethyl or naphthylethyl or benzyl or substituted benzyl R3, Rg, R?, Rg, R1q are hydrogen, Rg is carboxyl, and R11 is methyl, and y is 1 ^ ^ A I I and X is -CH- or -N- . We have found that the compounds as defined above with reference to Figure 1 including those excluded by the proviso are "useful in inhibiting en~kephalinase, as described with reference to the iri vivo and in vitro tests below. Representative examples of such compounds, in addition to those given above are as follows: 2 010 0 1 -17- N- (L-l-carboxy-3-phenvlpropyl) -L-phenylalanyl-L-alanine, N- (D,L-l-carboxy-ethyl)-L-phenylalanvl-L-alanine , N-(D,L-carboxy-3-phenvlpropyl)-L-phenyl-alanvl glycine, N- {L-l-carboxy-3-phenvlpropyl) -L—phenyl-alanyl-L—alanine, K- (L-carboxy-2-methyl propyl)-D,L.-phenyl-alanyl-L-alanine, N-(L)-l-carboxy-2-phenylethyl-L-leucyl-L-phenylalanine, N-(l-carboxy-3-phenylpropyl)-L-phenylalanyl-L-alanyl 1/2 isopropanol m.p. 164-164.5°C, N-(D-l-carboxy-3-phenylpropyl)-L-phenylalanyl-L- alanine m.p. 214-215°C, N-(L-l-ethoxycarbonyl-3-phenylpropyl)L-phenylalanyl-L-alanine or the maleate thereof m.p. 128-130°C (115-120°C), N-(l-carboxy-3-phenylpropyl)-L-phenylalanylglycinehemihydrate m.p. 140-145°C, N-(1-carboxy-1-methyl)-L-phenylalanylglycil and the hydrate thereof m.p. 125-132°C, and pharmaceutically acceptable salts thereof. The compounds of the present invention can be prepared by a number of methods as described below. -!<S- 2 010 0 1 one method for producing compounds in which R2 is other than 0=P-0R 10 R 11 5 Rfi I6 'C = N — X — CONCH(C) y R 8 A in which any reactive groups are suitably protected followed by removal of any protecting groups, if necessary, so as to provide a dipeptide of the formula: 5 I 6 "CH— NH— X — CONCH (C } R and, if desired, converting the so obtained compound of formula I into another compound of formula I e.g. by appropriate conversions of the groups R^ and for Rg. The above method may be carried out by reducing a Schiff's base as it is formed in a reaction mixture from a ketone acid or ester and an amino acid or ester according to the overall reaction. 20 f00 1 - 19 - h2N — X— CO V 5 R7 ' 6 MCH ( C )- R 8 R - C = N 1— X —CONCH ( C Ro R, + R] C=0 y In the above reductive condensation reaction X is preferably I 4 -CH-. For example, the reaction between the keto acid or ester and the priraar-" amine C can be carried out in solution using for example water or methanol as solvent under substantially neutral conditions in the presence of a .suitable reducing agent, for example sodium cyanoboro-hydride. - 20 - 2 010 0 1 Alternatively a Schiff1s base obtained by the reaction of the keto acid or ester C and the amino acid or ester D may be catalytically reduced in the presence of hydrogen at 1-4 atmospheres; suitable catalysts are for example Raney nickel and palladium on carbon e.g. 10%Pd . on carbon. Usually the group _Rg will be a protected carboxyl group e.g. benzyloxycarbonyl or lowexalko^cycarbonyl e.g. t-butyl-oxycarbonyl. In such instances the protecting group can be reduced giving a compound of formula I in which Rg is carboxy 1 ,"using conventional hydrolysis or hydrogenolysis - 21 - 201001 procedures, for example hydrolysis under basic conditions, for instance by reaction with sodium hydroxide in a suitable solvent. r / 20 When Rg is carboxyl it may be converted to the group -CON R21 to an alkoxy group by conventional procedures. For example, a compound of formula I. may be reacted with SOCl^ or oxalyl chloride to convert the Rq group into an activated ester group, and thereafter reacted with an amine HNR2QR21 or alcohol to obtain the desired compounds. Compound C can be prepared by following the reaction sequence- given below (the compounds in which X is Ra I -CH- are exemplified.) T< •nh— ch co2h R4 R5 h n I" I CHCONHCH(CH0) Rq 2 y y ?6 ?7 + H NCH(C ) - 2 I y R8 R r, Rr Rn 17 p — NH — h CH —OONHCH (C I r„ R, In the above reaction sequence the amino group of the amino acid F may be protected e.g. by any conventional amino protecting group-P,. for e.g. benzyloxycarbonyl or t-butyloxy carbonyl. - 22 - 2 010 01 The amino acid F can be condensed with an amino ester derivative G for example using a condensing agent such as dicyclohexylcarbodiimide (DCC) or diphenylphosphoryl azide. An activating agent, for example 1-hydrodybenzothiazole, 5 may be eraployed in the condensation reaction. The amino protecting group P. attached to the resulting dipeptide H is then removed by conventional treatment, for example, by treatment with an acid or by hydrogenation, for example, using hydrogen in the presence of a metal catalyst. *4 T2 'Q the case of those compounds in which X is -N- the reduction of the compound A may for' example be-carried out after isolation of the base of. formula: RK. ^2*4 ?6 R? C=N— N CONH Cf^C ) r T R—"" y 9 2 I 5 using a reducing agent e.g. sodium cyanoborohydride under weakly acidic conditions. The resulting compound of the formula ^H2R4 ?6 R7 R, CK NH N CONH—CH(C ) R„ 1 i R y9 2 8 can then be treated, as required to convert R if it is a protected carboxy group, by well-known methods such as; hydrolysis or hydrogenation to yield a terminal carboxy group, and likewise R /if it is carboxy protected can be converted, if desired, to carboxyl. The starting compound T can be formed by the following reaction sequence: - 23 2 010 0 1 o II PgOC - o NHNH2 + HC- R O II PgOC —NHN=CHR J K O (I PgOC- NHNH—CH2R^ M r7 R6 R9 (c) -CH-NH2HCI 5. R„ COCl. Rfi R7 I D I 7 -> 0=C=N- CH(CjI )-Rg R, O O CH^R. R R7 II I | 6 I PgOC—NH-N—CONHCH(C )- rn I Y 9 Ro CH R R R? 1 I6 I H N—N CONH—CH<C ) — Rr i . y 9 O 8 II Rl°-R2 Rr CH9R/ r,r-> -K I 2 4 j 6 17 C=N —N CONH —CH{C ) — RQ r i y 9 2 R8 T - 24 - 20100 1 In the foregoing reaction sequence, an N-protected hydrazine M is prepared by condensation of a protected-carboxy substituted hydrazine with an appropriately substituted aldehyde, isolating the resulting compound L and then 5 reducing it e.g. by hydrogenation, with hydrogen using a palladium-on—carbon catalyst, or by treating L with a reducing agent such as sodium borohydride. The resulting hydrazine M is then reacted with an appropriately substituted isocyanate to form the N—protected i C amino peptide P . Isocyanate O can be obtained by treating an <K-amino acid ester hydrochloride N with phosgene in a hydrocarbon solvent, as illustrated in the above reaction sequence, removing the solvent and distilling the residue. The protected carboxy group on the terminal amino group of compound 15 can then be removed by any standard method such as by acid hydrolysis using acetic acid or trifluoroacetic .acid, to yield the free amine R (see for example J. Chem. Soc. Perkin I, 246 (1976) ), which is then condensed with an appropriately substituted acid ketone or aldehyde S_ under -2 O basic conditions e.g. in the presence of sodium acetate, to yield the hydrazone T. For example, using pyruvic acid ethyl ester as ketone yields a hydrazone T in which R^ is -CH and R„ is -C00C„H . r in the above sequence may o '2 2 z> y for example,' be methoxy carbonyl. The resulting compound T can then 25 be reduced e.g. by treatment under weakly acidic conditions with sodium cyanoborohydride,to produce compound E. Alternatively the primary amine R^ can be condensed with ketone or aldehyde ^ in the presence of a reducing agent such as sodium cyanoborohydride under weakly acidic conditions e.g. SO in the presence of acetic acid, whereby the hydrazone T will be reduced, as it is formed, to yield the compound E directly. - 25 - £0100 b) The compounds of the present invention can also be prepared by coupling an amino acid ester having the formula: Rfi R7 i 7 h nch (c ) r 2 y 9 R8 with a compound of the formula: R3 I r— ch n —chr4 cooh 1 I r2 B in which any reactive groups are suitably protected, followed by removal of any protecting groups, so as to produce a dipeptide of the■formula R3 R7 R± ch n: chr4 — conhch (c ) y R9 R2 C1 and thereafter, if desired , converting the so obtained ompound of formula 1 into another compound of formula I - 26 - 2 010 0 1 In the case of the preparation of compounds in which X is ' l -CH- and R is other than 0=P—ORn „ a compound B' can ^ I lu R11 be subjected to reductive .condensation -an appropriately substituted amino acid with keto acid or ester according to the reaction scheme. R4 R4 I R,— C=0 + H NCH CO' H } R,— CHNHCH—CO^H 1 I 2 2 ' 1 - , 2 2 B Preferably, however,the compound B' is prepared by reductive condensation of an appropriately substituted keto acid with an amino acid ester according to the reaction. R4 R.— C=0 + R,— CHNH_ f R.. CHNHCHCO„H 4 , 1 | 2 lj 2 COOH R2 R2 These condensations may be carried out under the conditions described above in connection with the jreaction between compounds D and C in method a) . The resulting compound E is then coupled with an amino acid A' in which R is e.g. alkoxy carbonyl or dialkylamino carbonyl or other non-reactive group within the above definition of Rg. Route b) is suitable for those compounds in which R is l 2 0=P — OR^q . A starting intermediate B' for such compounds is^ 11 - 27 - 201001 e.a. the compound l4 r.— ch— nh- ch co„h 1 , 2 °^-°Rio R11 D- in which is alkyl or benzyl. Compound D' can be prepared for example by reaction of an amine 5 R, CH—-NH9 1 I °=P—°Rio R11 p' I4 with a substituted pyruvic acid of the formula O—C CO2H to form a Schiff*s base which is reduced, preferably with sodium cyanoborohydride to form compound D1 . The compound A' which is reacted in this particular procedure with i O compound D* is for example an appropriately substituted amino acid (i-e. Rg is COOMe), the conditions for instance using a condensing agent e.g. DCC. 15 Appropriate selection of protecting groups as Rg and R ■ enables the resulting compound selectively to be de-protected at the group R , by conventional procedures, to provide a terminal carboxyl group in which R^ is carboxyl, with leaving the group R P°5^t;^on if desired; if desired however, both Rg and -2"0 -OR10 can for example, be hydrolysed to hydroxy under alkaline conditions. - 28 - 2 010 0 1 Compound B' can be coupled with an amino acid A' using standard techniques e.g. carrying out the reaction by first forming an activated ester group by reaction of B' with an activating agent such as 1-hydroxy-benzotriazole, followed by reaction with compound A' and treatment with a condensing agent such as 1—T 3-"dimethyl-arninopropyl) -3-ethylcarbodiiinide hydrochloride. c) A further method for preparing compounds in which ra 14 X is —CH— comprises reducing a compound of the formula K R_ I4 r i R,— C— N=C — C0NRc - CH— (C •)■— R l I 5 | y k7 R2 .. R8 in which, .any reactive groups are suitably protected so as to produce a compound of the formula H R. R R I l4 I6 i7 ■ R.— CH— N CH CCNRt-CHfC: )-— r if ( y 9 Ro 2 8 G* followed by removal of any protecting groups. This method is conveniently carried out by condensation of a ketone of the formula ra r-7 i4 i i7 0=C—CONRj. — CH—(C )— Rn 5 \ y 9 "R 1 with an amino acid or ester of the formula - 29 - 2 010 0 1 H r. nh. r. f 1 5 in the presence of a reducing agent e.g. sodium cyanoborohydride. If desired, the resulting compounds G1 having a terminal carboxy group (r --COOH) , and preferably those in which r„ 9 ^ is other than 0=P—OR^o can ^:ur't:^er treated by procedures r 11 described above to form another compound of formula 1 by appropriate conversion of the functions R2 and for Rg. Q The intermediate E' in which Rqg is -COOH can be prepared by following the reaction sequence given below: R'4~ CHO + CH2CO2H NHCOCH. H ' NaOAC Ac 2 0 H3° h2° r* CH 4 ± N O CH. R; h2nch—r9 O R^ R 11 1° 17 R1 CH=C— C—NHCH (C ) R, 4 | i NHCOCHj 8 y 9 K1 - 30 - 20100 1 in which R'^ is a group which together with a methyl group by which it is attached to the peptide chain of the resulting compound E' constitutes an R^ group. N-Acetyl glycine H' is condensed with an, appropriately R^ substituted aldehyde (preferably an aryl or heteroaryl or heteroaralkyl aldehyde) in the presence of acetic anhydride/sodium acetate, to yield the substituted azlactone J" which is in turn reacted with an amino acid A to yield the R^_ substituted N- acetyl dehydro dipeptide "which in the presence of aqueous acid is converted to the corresponding R^, R^ substituted, pyruvoylamino acid E'. Alternatively the starting compound E' may be prepared by condensing an R^- substituted pyruvic acid with an amino acid ester under the influence of dicyclo- hexyl carbodiimide (DCC) followed by alkaline hydrolysis of the resulting ester according to the reaction sequence: R4 R7 R/ R A R7 I || DCC | | 6 |7 0=c—CO.H + H„NCH(C ) . RQ * 0=C— CONHCH(c ) R0 2 2 | y y ■ y 9 R8 ° L1 M' N' Rr in compound. M' may for example be carbomethoxy D Hydrolysis of an ester N' gives the free keto acid R. Ra R-, j 4 , 6 , 7 0=C— CONHCH(C ) CO_H i y 2 O" R8 IO 31 - 20100 1 In the case of those compounds in which is O—P ^R^q R, method c) can be practised using corapounds in which R^q 11 *io is other than hydrogen i.e. benzyl or lower alkyl- The corresponding compounds in which R^q "*"s hydrogen can readily 5 be obtained by reducing R^q when it is benzyl, and when it is alkyl by basic hydrolysis, using conventional techniques. Intermediates wfiich can be used, to .produce compounds in accordance .with. the invention by this procedure have the formula: R, CH NH_ in which R, n .I j 2 J- U °=p-°ri0 R II is not hydrogen^ and will generally be condensed with a compound of formula E" in the presence of a reducing agent such as sodium cyanoborohydride. The aforesaid intermediates can be prepared for example, by reacting together an substituted aldehyde, ammonia and an R^ substituted alkoxy or benzyloxy phosphonic or phosphinic acid. d) Yest a further method for the preparation of compounds of the invention, comprises" reacting an amino acid or ester having the formula - 32 - 20100 1 H *6 *7 R N_ X —CONR,CH (C ) R 3 3 , y q S 8 in which X, and the various substituents are as defined above, with a compound of the formula V Hal— CH T' I R2 an which any reactive groups are suitably protected, and Hal represents halogen e.g. chlorine or bromine, I4 If desired, preferably when X is —CH- , when R is carboxyl the Rg group may be converted to an alkoxy group or the group -NR2OR22 by the procedures mentioned above. The reaction of the alkylating agent T* with intermediate S_ can be carried out under conventional alkylating conditions preferably in the presence of a .base, e.g. a tertiary amine or an inorganic hydroxide, carbonate or bicarbonate- The reaction is usually carried out in water or an organic solvent such as dimethyl formamide or acetonitrile. <?h2H In the case of the compounds in which X'is -N— compounds in which R3 is hydrogen may be prepared by following the reaction sequence given below by way of example: - 33 - 2 010 0 1 CH. o II OC R i6 CH u O II -NHC R4 -N NH0 + HalCH2CQ2CH3 O Ra ii i6 f* O (CH-) II I 2 CH-lO — C — CH— NHC— N — NH — CH W f co2ch3 Hydrolysis of the methylated carboxyl groups yields the compounds in which Rg is carboxy and R2 is -COOH. The halide is preferably chlorine or bromine. e) Yet a further method is available for preparing those compounds of the invention in which R„ is O—P — OR Z | -LU R11 which comprises reacting a phosphite ester or phosphonate ester with a compound A" as shown below: O li H— P —OR 10 Rfi R7 1 1 + R-— CH=N-X —CONHCK (c 1 I R8 A" t R. R6 ^7 R. CH NH— X CONHCH (C )y R I i i - 0=P— OR 10 Rc 11 b" - 34 - 2 0100 1 in which R^q is not hydrogen, and R ^ is a protected carboxy group e.g. methoxy, and any other reactive groups in may be suitably protected, followed by removal of the protecting groups as required. 5 The resulting compound B" may be treated to remove the protecting group Rg so as to provide a terminal carboxylic group • " Also the group R^Q may if desired be replaced by hydrogen. For example, treatment of compound B" in which Rg is lower aUc/loxycarbonyl e.g. methyl, by hydrolysis, iO under basic conditions yields compounds of the invention in which hydrogen and Rg is carboxyl. The immediately preceding method is particularly suitable for those compounds in which R4 R/ I 4 I 4 X is -N- and also those in which X is -CH- and R. 4 is hydrogen, aryl, heteroaryl, adamantyl or indolyl directly attached to the carbon of the peptide chain. The present invention comprehends the salts of those compounds of formula I containing one or more free acid or basic -groups, with inorganic or organic acids or bases. Such D- O salts include, for example, alkali metal salts e.g. sodium and potassium salts and salts of organic and inorganic acids, for example, HCl and roaleic acid. The salts may be formed by known methods, for example, by reacting the free acid or free base forms of the product 2--t> with at least one equivalent of the appropriate base or acid in a solvent or reaction medium e.g. ethylacetate, in which the salt is insoluble, or in a solvent which can be removed in vacuo or by freeze-drying. 20100 - 35 - When the reactions described above, either for the preparation of intermediates or the final desired compounds of the invention, involve the generation of water, e.g. condensation reactions; these reactions may be carried out 5 under azeotropic distillation with a suitable high boiling solvent e.g. toluene or oxylene, or in the presence of a dehydrating agent e.g. a molecular sieve. Various intermediates for the preparation of the compounds of the invention by the methods described above are iC commercially available e.g. from Chemical Dynamics Corporation or their preparation is also described in the peptide or general chemical literature e.g. J.H. Jones Comprehensive Organic Chemistry, Vol. 2. p. 819 - 823 1979; references 2 and 29-31, and Tetrahedron Letters No. 4, 19787 p.375-378. - 36 - 2 010 0 1 The compounds defined above may possess centres of chiralitv at their ' asymmetric- carbon' atoms. Generally, the corapounds produced by the processes described herein will be diastereomeric mixtures of compounds 5 which are respectively 'D' and 'L' at least at one of the said centres of chirality. Separation of such diastereomeric mixtures may be carried out by techniques well known in-the art. For example, the respective compounds can be separated by physical means 10 such as crystallization or chromatography, or by the formation of diastereomeric salts followed by fractional crystallisation. The invention is concerned with all stereomeric forms of the dipeptide compounds set forth herein. IS Those compounds having a configuration similar to that of natural L-amino acids are preferred. Usually natural amino acids are assigned the ^.configuration according to the Cuhn-Ingold Prelog system. A notable exception is the natural amino acid Cysteine which has the R configuration. - 37 - 2 010 0 1 Dipeptide compounds as defined herein inhibit the activity of enkephalinases. Some of these compounds have been found useful in inhibiting Enkephalinase A derived from the striata of rats. In iri vitro tests, such compounds, _ 9 — 6 vhen used in a concentration range of 10 to 10 M/ have reduced the activity of the aforesaid enzyme by 50% or more. The ^nkephalinase used in the aforesaid tests was obtained by separations from the brains of young male Sprague-Dowley rats using the procedure described by C. Gorenstein etr al. in Life Sciences, vol., 25, Pages 2065—2070, pergamon Press (1979). In this procedure the various enkephalin degrading enzyme activities in brain are resolved from one another following a procedure described by Gorenstein and Synder (Life Sciences, Sciences, Vol. 25, pp 2065-2070, 1979). The brain (minus cerebellum) from one young Sprague-Dawley rat was first homogenised • in 30 volumes of 50 mM Tris buffer, pH 7.4, The resulting homogenate was centrifuged at 50,000xg for 15 mins and the pellet,, constituting the membrane-bound enzyme material, resuspended in Tris and washed and centrifuged as described above four times. The membrane pellet was solubilized by incubating it for 45 mins at 37°C. in the presence of 15 volumes (based on initial brain weight) of 50mM Tris — 1% TRITON X-100 buffer pH 7.4. After centrifugation at 100, OOOxg for 60 mins to remove non-solubilized material, the Triton-soluble super-r natant was layered on a 1.5 x 30 cm DEAE Sephacel column previously equilibrated with 50mM Tris — 0.1% Triton, pH 7.4. Material was eluted form the column using a -1 litre linear NaCl gradient running from 0.0 to 0.4M. Eluant was collected - 38 - 20100 1 in 7ml fractions, each of which was assayed for enkephali-nase acitivity. Under these conditions enkephalinase "A" activity (dipeptidyl carboxypeptidase) is found to elute between 120 and 220ml, followed by aminopeptidase activity (260 to 400ml) and finally enkephalinase "B" activity (dipeptidyl aminopeptidase) between 420 and 450ml. In the array enkephalinase activity was monitored by radio-metry. The substrate was 3H-met'-enkephalin (50.1 Ciymmol, NEN) diluted in 0.05M Tris buffer, pH '7.4, such that the final reaction mixture "concentration was 4 0nM- Total reaction mixture volume including enzyme and substrate was 250ml. Incubation was carried out for 90min at 37°C. To kill the reaction, tubes were transferred to a boiling water bath for 15min. A 4ral aliquot of the reaction mixture was then spotted on a Baker-Flex Silica Gel IB plate (20 x 20cm) along with unlabelled-standards of met-enkephalin, tyrosine, tyrosyl-glycine, tyrosyl. glycyl-clycine) and the components co-chormatographed in an isopropanol: ethyl acetate: 5% wt/vol acetic acid solvent system (2:2:1) which is capable-of resolving met-enkephalin from its breakdown products. Total running time was approximately 17 hours. TLC tanks were gassed with nitrogen prior to starting the run. Following the run, the markers were visualized with ninhy-drin spray. These spots along with remaining plate regions were cut from the plate and the radioactivity corresponding to each spot monitored through scintillation counting. - 39 - 2 010 0 1 Thus the amount of radioactivity in the spots containing respectively Tyr, TyrGly, TyrGlyGly, and "undigested met-enkephalin, was determined. For each plate, the radio-activity of each spot produced therefrom can be expressed as a percentage of the total iz? - radioactivity recovered from the plate. To eliminate the effect of natural decomposition of met-enkephalin in the absence of enzymes, the percentages of the radio-activity of the Tyr, TyrGly, TyrGlyGly spots of a non-enzyme blank are subtracted from the corresponding j-Q values obtained for the experimental samples from each of the runs using enzymes; the resulting values are summed to give net product percentages for each run. In order to obtain figures for making comparative evaluations of different dipeptide species, for each species the IJ5 net product percentage (P) formed, in a run in the presence of a respective species and the net product percentage (A) formed in a test run in the absence of the species can be substituted into the formula (A-P)/P. The resulting values for different species are used to provide an indi— _2"Q cation of the comparative inhibiting activity of the various dipeptides. u0 2 010 01 - yf Also, in in vitro tests, such compounds, when parenterally administered in the dose range of 5 to 100 mg/kg to mice, have been observed to potentiate the analgesic effects if intra cerebrally administered -D-Ala-met-enkephal inami de . 5 Pharmaceutical compositions may be in any of the forms known in the art, for exampl e, tablets, capsules or elixirs for oral administration, and sterile solutions or suspensions for parenteral administration. The dosage forms are advantageously prepared using, in IO addition to the active dipeptide, a pharmaceutically acceptable and compatible carrier or excipient, binders, preservatives, stabilizers and flavouring agents. The dosage forms will usually be prepared such as to facilitate the administration of the active compounds in a '5 dosage in the range of from 5 to 100 mg/kg, such doses being administered at intervals of 3 to 8 hours. Typical acceptable pharmaceutical carriers "for use in the formulations described above are exemplified by: sugars such as lactose, sucrose, mannitol and-sorbitol; starches such as corn starch, tapioca starch and potato starch; cellulose and derivatives such as sodium carboxymethyl cellulose, ethyl cellulose and methyl cellulose; calcium phosphates such asvdi—calcium phosphate and tri—calcium phosphate; sodium sulfate, calcium sulfate, polyvinyl-ZLS pyrrolidine, polyvinyl alcohol, stearic acid; alkaline earth metal stearates such as magnesium stearate and calcium stearate, stearic acid;vegetable oils such as peanut oil, cotton seed oil, sesame oil, olive oil and corn oil; cationic and anionic surfactants; ethylene glycol polymers; -SO beta-cyclodextrin; fatty alcohols and hydrolysed cereal solids. - MT - 2 0100 1 The following Examples illustrate the invention EXANPLE 1 Preparation of L-3-(3'-thienyl)alanyl-L-alanine trifluoro- acetate salt. a) N-tritertiarybutyloxy -L-3- (3 ' thienyl) alanine . 2. Og(11.68mM) of L-3-(3'^thienyl)alanine . (Chemical Dynamics • Inc.) were suspended in 1.6ml-triethylamine, and 2.6g of di-tertbutyl dica'rbona te were .dissolved in a ^mixture- of 22ml of dimethylformarnide (DMF) -and :22ml of methanol (which had previously been dried over a molecular sieve. The DHF/methanol solution /as 3dded to the suspension with stirring and stirring was continued over a further-period of 24 hours at ambient temperature. The resulting, homogenous solution was diluted with 330ml of water and then acidified with citric acid. The resulting solution -was extracted 4 times with 80ml of ethyl acetate,, the extract was washed with water, then with brine/and dried over magnesium sulphate. The solvent was evaporated to -give 3.2g of the title produtt. b) N-tritertiarybutyloxy -L-3- (3 ' -thienyl) alanyl^L-alanine ■ ethyl ester. The 3.2g (11 w68mM)' of i title product from step a) were suspended, together with 1.8g of L-alanine ethyl ester hydrochloride (Sigma Chemicals)' and 3.3g hydroxybenzyltriazole in a mixture of 20ml dimethylformarnide and -2. Oral> of -triethylaraine with stirring'at ambient temperature. . 2.5gof. N- (N,N-dimethylaminopropyl)-N'—ethylcarbodiimide hydrochloride and 2ml of triethylaraine were then added to the suspension and the iresulting mixture•was stirred overnight; 300 ml of water'was then added to the reaction mixture which was thereafter extracted 4 times with 60ml ethyl acetate. ^ 2 010 0 - A - The combined extracts were washed twice with 70ml of IN sodium bicarbonate, twice with 30ml of IN citric acid, twice with 70ml of water, and once with 70ml brine. The resulting extract was dried over magnesium sulphate and S the solvent evaporated to give 5.1g of the title product. c) N-tri tertiarybutyloxy__L-3- (3 ' -thienvl) alanvl-L-alanine 4.4g (11.8mM) of the title product from step b) was dissolved in 30ral of methanol. 30ral water was added to the solution followed by l.lg (14.2mM) of NaOH in the form of a 50% wt iO by volume aqueous solutionl The reaction mixture was stirred at ambient temperature and after one hour a sample was checked for starting material using thin layer chromatography (tic) on silica gel using a mixture of methanol, chloroform and acetic acid in a volumetric ratio of 5:95:0.5 as the mobile phase. Stixring was continued and the reaction mixture monitored in this way until completion of the reaction was indicated by the absence of starting material . The reaction mixture was then concentrated under reduced pressure and the residue was mixed with 30ml water; the J>0 resulting aqueous solution was washed twice with 30ml of methylene chloride and then acidified to yield a gummy precipitate. This precipitate was extracted with ethyl acetate and the extract dried over magnesium sulfate after which the ethyl acetate was evaporated to give 5. 8g of the -2.S title product. d) L-3- (3'-thienvl)alanyl-L-alanine trifluoroacetate. The 5.8g of the title product from step c) was dissolved in 15ml methylene chloride with stirring. 15ml trifluoro-acetic acid was added to the solution and the mixture was 3,0 stirred for two hours at room temperature. The reaction mixture was monitored by tic on silica gel using a mixture of methylene chloride, methanol and acetic acid in a volumetric ratio of 95:5:0.5 as the mobile phase. % 4? - 42 - 2 010 0 When tic Indicated the absence of starting material the reaction mixture was concentrated to a gummy residue which was dissolved in benzene and distilled to a residue, dissolved again in benzene and distilled yet again to give 5 7g of the title product. e) N-(l-carboxy-3-phenyIpropyl)-L-3-(3-thienvl)alanyl- L-alanine A solution of L-3—"(3-thienyl)alanyl-L-alanine trifluoro-acetate (4.75g, 13.4 m.mol) and 2-oxo-4-jphenylbutyric jacid IO (11.0g, -56.1 xn.mols) in water was adjusted to pH 6.8 by addition of IN NaOH, Sodium cyanoborohydride (2.2g, 34.8 m.mol) was added in a single portion to the solution and the resulting reaction mixture was stirred at room temperature for 64 hours. The pH of the resulting '5 solution was then adjusted to 2-9 by the addition of IN Hd. The guramy product which separated from the solution was washed several times with water. The gummy product was then dissolved in 20ml of acetonitrile and the solution diluted with 10ml of ether. Upon cooling a solid separated •20 and this was collected by filtration. The mother liquors were stood in a refrigerator for two days by which time a white solid had deposited: this. solid was filtered off, washed with acetonitrile and dried to yield the N-(L-l) diastereoisomer of the title compound having a m.p. of -2j5 192.5°C. - 193°C. The first mentioned solid was recrystallised from ethanol to give the N-(D-l) diastereoisomer. having a m.p. of 163°C. 164°c. _ >4_ 2 0100 EXAMPLES 2 TO 7 By following procedures similar to that of Example 1, using appropriate starting materials, the following compounds and diastereomeric mixtures were prepared: 5 2) N-(L-l-carboxy-3-phenylpropyl)-L-phenylalanyl- L-alanine, m.p. 176°C. - 17 9°C; 3) N- (D, L-l-carboxy-3-phenylpropyl) -L-3— (2 ' —naphthyl) o o alanyl-L-alanine, m.p. 149 C.-155 C. 4) N-(L-l-ethoxycarbonyl-3-phenylpropyl)-L-3-(2 •- ' O thienyl) alanyl-L-alanine maleate, m.p. 124°C..-125 5) • N—(D,L-l-carboxyl-ethyl)-L-phenylaianyl—L—alanine, m.p. 125°C.-135°C. 6) N- (D-l-carboxy—3-phenylpropyl)-L-(4-fluorophenyl) alanyl-L-alanine, to.p. 147°C.-152°C. '5 7) N- (D, L -l-carbo^cy-3-phenylpropyl) —L-phenyl-alanyl- glycine, m.p. 140°C.—145°C. EXAMPLE 8 - 15g (0.07m) of phenylalanine anethyl estex hydrochloride were dissolved in 400ml methanol. 2.4g (0.105:m) of so--2'0 dium phenyl pyruvate, followed by 15g powdered 3A molecular seive (Aldrich Chemical) were then added. The slurry was stirred at ambient temperature while 6.6g (0.105m) of sodium cyanoborohydride in 75ml methanol l\s - 2 010 0 1 were added over a period of 6 hours. The slurry was thereafter stirred for 2 days, then filtered and the filtrate concentrated to "a syrup. 300ml of 2 1/2 per. cent, hydrochloric acid were added to the syrup over 3 hours "and the" resulting white crystals filtered and dried under reduced pressure to constant weight. A" representative s-ample of the dried product was chromatographed on silica gel" "thin, layer plates "using as solvent system a chloroform: methanol: concentrated hydrochloric acid /■Q mixture "(50:15:1 volumetric ratio) to ascertain the approximate "ratio of the" diastereoisoroers. The chromato-gram showed approximately a -50/50 mixture of" diastereo-isomers with some "3-phenyl—2—hydroxy propionic acid present. I^> Yield: 24 g; m.p. 119 —130 C. « NMR consistent with "the desired product. Upon crystallisation from.400ml ethanol 14.7g of desired compound (again in the" form of a diastereomeric mixture) was obtained enriched with the faster moving isomer (as : o 20 determined by thin layer chromatography (tic) }/ M-P- 135— 150"c. 200mg of the enriched diastereomeric mixture was recrystal-lized from 3ml of ^methanol ~to ^ield lOOmg .crystals which ^ 20100 1 were nearly pure faster moving isomer (as determined by tic) M.P. 169°— 172*C. ' 14.5g of the enriched diastereomeric mixture was subjected to a recrystallisation procedure using 4 007nl methanol but no crystals "formed. The solution was concentrated to 200ml,. seeded and allowed to stand. A gelatinous precepitate formed which was shown by tic to be a mixture of isomers with the slower moving isomer predaminant: yield 7.0g.3.Og of this product we're 'subjected to high 'performance liquid chroma to g-raphy (hpic) "on" Waters Prep. 500 Equipment using two silica gel columns in series., with a solvent system consisting of chloroform: methanol: -ammonium hydrox'ide (500 : 150:10 volumetric ratio) at a flow rate of 0.2 litres per minute.' " Fractions 8 and 9 yielded 450mg of isomer I (see below Fraction 10 yielded 400mg of material which upon recrystal-lisation from methanol yielded 150mg of isomer I. Fractions 12 to 15 yielded 1.2g pure, isomer II (see below) . Fraction 11 yielded a mature "of isomer I and isomer II. HPLC was carried out on another 3.5g of the same product as in the preceding par-agraph using the "same solvent ratios and absorbents. -Fraction 4 yielded 400mg of pure isomer I, Fraction 5 yielded l.Og of material which when recrystallised from methanol yielded 550mg of substantially pure isomer I, fraction 6 yielded 0.4g of jnaixture of isomer I and isomer IIffractions 7 to 10 jyielded 1.6g of pure isomer IX Isomer I M.P. 171* - 173 C. Mass Spectrum M+l 328 282 (M-COOH) 268 (M-COOH3) "236 (M-91) 2 010 0 1 Forraul a HC—NH—CH.COOH i COOCH^ • & Isomer II H.P. 14 9 —151 C Mass Spectrum >5+1 * 328 282 (M-COOH) . 268 (M-COOCH^) The filtrate obtained upon filtering the gelatinous precipitate was concentrated to 50ml and 100ml of- acetonitrile ■were added thereto with cooling^resulting in precipitation of l.Og of white crystals id.P. 167 — 170 jC. These crystals were recryst-allised from methanol* 0.7g of white crystals, M.P. 171-173*C were "obtained. 2 010 0 1 IO 15 15 L-K-" ^(I-carboyy-2 phenyl) e thyl ~-ph en y l a I an y 1 —J3 - a 11 n 1 h e methyl ester l.og (3.05mM) of Isomer I were dissolved in 20ml of dimethyl-forroamide (ctraf) then were added 520mg (3.4mM) of 1—hydroxy— benzotri azolehydrate (HOBT H^O) followed by 4 72mg (3.4mM) of ^-alanine 'methyl ester hydrochloride, 1.3ml (equivalents) of N—ethylmorpholine (NEW) and 64f?mg (3.4mM) of N-(3-di-methylaminopropyl) —N—ethylcarbodlimide hydrochloride (EDCL) . The resulting solution" was stirred at room temperature for 4 8 hours "and then poured into "150ml of Ice water with stirring and the aqueous solution extracted twice with 150ml of . ethy'lether. The ethylether layer was washed three times with lOCtral of water, then with water to which a few drops of HCL had been added, and then finally with water. The ether layer was dried over magnesium carbonate, filtered, and the filtrate concentrated to a gum; Yield l.lg of title product. l;-N- ~|~(1—carboxy-^-phenyl) ethylj —phenylal'a^nyl -j3-al"anlhe The gum from the "previous step was dissolved in 20ml metha-O nol and 6.6ml of IN sodium hydroxide "added dropwise over a period of 10-minutes with stirring and external cooling. The solution .was allowed to stand overnight (15—20 hours) at room temperature. The 5 per. cent, hydrochloric acid solution was added dropwise. until the pH of the. solution reached 2.5 (the solution being stirred during this addition) whereupon a white solid slowly precipitated. The solution was filtered and the precipitate dried under reduced pres — sure, at 4 0 C.j to constant weight. • c'\ iv I 2 0 10 0 t Yield 90Omg, .M.P. 218-219 C. Mass Spectrara _M/e 385 (M+l) 367 (H+l-18) 34 0 (M+l-COOH) 339 (M-45-COOH) 293 (>5-91). EXAMPLES 9 TO 15 By following procedures similar to that of Example 8 using appropriate starting materials, the following compounds and diastereomeric mixtures were prepared. 9) ^-(L-l-carboxy-3-phenylpropyl) -D,L-3— (1-naphthyl) alanyl-L-alanine m.p. 186°C. - 194°C. 10) N- (L-l-carboxy-3-phenylpropyl) -L-3- (1-naphthyl) alanyl-jJ-alanine, 6o - - 20100 1 11) N- (L-l-carboxy-2-methylpropyl) -D, L-phenyl-alanyl-L-alanine m.p. 160°C. - 172°C. 12) N- (L-l-carboxy-2- (benzylthio) -ethyl) -L-phenylalanvl-/3-alanine in.p. 152°C . - 154°C. 13 ) N- (L-l-carboxy-13- phenylpropyl) -L-phenylalanyl-L-alanine 14) N-(L-l-carboxy-2-phenylethyl)-L-phenylalanyl-^f -amino butyric acid ra.p. 209°C. - 211°C. 15) N- (L-l-carboxy-3-phenylpropyl) -L-phenyl-alanyl-0-alanine hemihydrate m.p. 176°C. - 190°C. 201001 EXAMPLE I 6 N- (D, L-1 -carboxvethyl) -L-phenyl alanyl glycine . To a solution of 0.6g (2.5m.mol) of L-phenvlalanylglycine in 5ml of IN NAOH and 20ml water is added dropwise over a period of 1 hour a solution of 0.25g (2.5m.mol) 2-chloropropionic acid in 5ml of IN NaOH; during the addition the reaction solution is maintained in the temperature range of from 80°C. — 90°C, and the pH thereof in the range of 8-9. Gn completion of the addition the reaction mixture is maintained, by heating, for 15.-minutes at 80°C. - 90°C. and then' evaporated to dryness under reduced pressure and neutralised with 5% wt/vol. aqeous hydrochloric acid. Upon re-evaporation to dryness a grey solid is obtained. The grey solid is stirred with ether which is then decanted; and the solids are then stirred with cold ethanol. Undissolved solids are filtered from the ethanol solution which -*-s evaporated to dryness to give o o the title mixture of diastereomers. m.p. 90 C. — 120 C. S& - &£ - 2 010 0 1 EXAMPLE 17 a) Preparation of butyloxycarbonyl-hydrazine To a stirred solution of 0.1ml hydrazine hydrate in 15ml isopropanol was added dropwise a solution of di — t—butyl dicarbonate in isopropanol (the solution having a concentration of 0.45ml of dicarbonate in 7ml of the propanol) -The addition was at the rate of one drop every 7 seconds. The reaction was stopped after approximately 6/7ths of the .t-butyldicarbonate had been added. The mother liquor was evaporated, and the resulting solid was chromatographed on silica gel using a mixture of chloroforra/raethanol in a volume ratio of 97:3 as the mobile phase. Fractions 20 to 33 were collected which after working up in conventional manner yielded 0.105g of the title product as a solid m.p. 34°C. — 35 °C. Re-crystallisation from ether/petroleum ether yielded a solid with m.p. 36.5°C. -- 37°C. b) Preparation of N-benzylidene-Nl-T-butyloxycarbonylhydrazine 3.47g of the title product from a), "were "dissolved in 30ml of ethanol with stirring and 2.79g benzaldehyde were added. The reaction mixture was heated in a steam bath with stirring for 10 minutes then chilled in an ice water bath. The resulting reaction mixture was filtered.to yield the title "product (3.50g). 53 -pf- 201001 The mother liquor was evaporated to a solid which after washing with hexane and filtering yielded 1.56g solids. The two fractions were subjected to thin layer chromatography on silica gel plates using chloroform/methanol 5 in a volume ratio of 97:3 as the mobile phase. Subsequent tests revealed that the two fractions were substantially identical products. The total yield was 5. 06g. m.p. 190°C. - J.94.5°C. c) Preparation of N-benzyl-Nl-T-butyloxycarbonyl hydrazine /C1 lg of the title product from b) - was dissolved in 30ml tetrahydrofuran. 0.23g_ of a 5% palladium-on-carbon catalyst was added and hydrogenation was carried out for approximately 15 minutes. The reaction mixture was filtered and the mother liquor evaporated yielding 0.96g 15 of the title product. ' d) Preparation of L-iaethyl-2-isocyanato-4-methylvalerate 7g. of L-leucine methyl ester was suspended in 200ml toluene which had previously been dried over calcium 2.0 hydride. The suspension was stirred and an excess of phosgene gas bubbled .therethrough • After the solids had dissolved the temperature of the reaction mixture was raised to, and maintained at, reflux for a period of half an hour. ^ After cessation of heating nitrogen gas was bubbled throiagh the resulting solution to remove the excess phosgene and hydrogen chloride reaction product dissolved in the solution. After this operation the solution was evaporated and the resulting liquid product distilled. - 201001 [a]^ = -25.55°C. (C=5.7% in toluene) (literature -22.4 C. Annalen 1952/ 575/ 217) -b-p. 71°C. - 72°C. "(45mm Hg) N-t-butyloxycarbonyl-ol -azaphenylalanyl-L-leucine methyl ester 2.47g of product of beHzylhydrazino-t-butylcarboxylate product of step c) was dissolve! in 15ml toluene with stirrinc. Then 1.9g of product of step d was added, followed by the addition of 1.12g of triethylamine, to the reaction solution- The resulting reaction mixture was stirred for 16 hours, after which it was diluted with 200ml of ethyl acetate, washed once with 5% wt./vol, aqueous solution of citric acid, then once with brine, and finally once with water. The solution was dried over sodium sulphate, and, after filtering off the sodium sulphate, was concentrated to a residue which was chromatographed on 75g of silica'gel using a 7/3 by volume mixture of hexane and chloroform as the eluant. After working up in conventional manner 3 .72g of the title product was obtained. ^ —7.1° (c—3.29% in chloroform). 55 - - 201001 f) o-azaphenylalanyl-L-leucine methyl ester 8.0 ml of an anhydrous mixture of HCl/CH^COOH (volumetric ratio 1/80) was cooled to 4°C. under stirring and the product of step e) was added thereto. Stirring was continued at 4 °C. for 20 minutes after which the solvent was removed under reduced pressure. The residue was subjected to thin layer chromatography on silica gel using a chloro-form/methanol mixture (98/2 v/v) as the eluant. Appropriate fractions with corresponding rf values wece combined yielding 26 o 0.163g of the title product £ al^ = +1.9 Mass spectrum JM+2 93 (—HCl) 262 (-m-OCH-,) 234 (-m-C02CH3) g) N-(D , L-l-ethoxycarbonyl —3-phen'yl—Propyl) —g-azaphenyl ' al'anyl-Ii-'leucine methyl ester 0.151g (0.458m.mol) of the title product from step f) was dissolved in 3ml methanol and 83.4mg of ethyl-4— phenyl — 2-oxobutanoate was added thereto with stirring at 60°C. The reaction was monitored by tic using silica gel plates and a chloroform/.acetone mixture (9/1 by volume) as the eluant. Upon substantial completion of the reaction 70mg of sodium cyanoborohydride and 4 drops of a 10% wt/vol aqueous solution of acetic acid.were added. The reaction was monitored by tic using silica gel plates and a mixture of chloroform and methanol (98/2, by volume) as the eluant. A further 70mg of sodium cyanoborohydride and 4 drops of acetic acid solution mentioned above were then added. 5w. - - 20100 1 The reaction solution was allowed to stand for 16 hours, after which the solvent was removed under reduced pressure. 40ml ethylacetate was added to the residue, the resulting solution washed with 20ml of aqueous sodium chloride and then twice with 20ral water. The organic solution was dried over magnesium sulphate and filtered and the solvent removed under reduced pressure. The residue (0.277g) was chroroatographed on silica gel using a mixture of hexane/chloroform (.7/3 by volume) as the eluant. Appropriate fractions were "combined according to their thin layer migration to give the title product. h) N- (D, L-l-carboxy- 3-phenyl -propyl ) -g-azaphenylalanyl- L-leucine X).428g (0.265m.mol) of the title compound of step g) was 0 dissolved in 10ml aqueous acetone (acetone/water, 3/1 by volume) 1.06ml of aqueous sodium hydroxide solution (containing 1.06m.mol NaOH) was added to the reaction solution whilst stirring. The reaction was monitored using tic with a chloroform methanol/amraonium hydroxide in a 1:1:1 volumetric ratio as the eluant. An additional 0.04ml of concentrated sodium hydroxide (containing 0.4m.mol NaOH) solution was added and the monitoring of the reaction continued until the reaction was substantially complete. 10ml of water was added to the reaction mixture which was extracted twice "with 30ml portions of ethyl acetate. The extracts were combined, dried and concentrated to a residue. The residue was chromatographed on silica gel using the lower phase of chloroform : methanol : ammonium hydroxide mixture (2:1:1 volumetric ratio) as the eluant. Gn 20100 1 Appropriate fractions were combined according to their rf values. The combined fractions were "* recrystallised from diethyl ether, the mother liquor from the first jecrystal-lisation being further concentrated to provide a second crop of crystals. The total yield of title compound was 4 3mg. - .srf'- 2 0 10 0 1 EXAMPLE 18 NH N ?H2C6H5 CH CH(CH-,)0 j Z -o jL CONHCHCOOH 0=P— OH A solution of a-azaphehylalanyl"-L-leucine methyl ester (see Example 17) and one equivalent (with respect to the ester) of benzaldehyde in anhydrous methanol is allowed to stand over a 3A type molecular sieve for 16 hours. To-the resulting solution is added one equivalent (with respect to the ester) of ethyl- phosphonic acid ethyl ester and a trace of sodium methoxide. The reaction solution is then allowed to stand for 6 to 8 hours. The molecular sieve material is then removed by filtration and the filtrate is concentrated under reduced pressure. To the concentrated solution is added 2.1 equivalents (with respect to the ester) of sodium hydroxide in the form of a IN aqueous solution, and the mixture is stirred for 6 hours at room temperature. The organic solvent is removed under reduced pressure and the residue is diluted with water. Insoluble material is extracted with ethyl acetate and the aqueous solution is acidified to pH 2.5 by the addition of IN HC1. The resulting precipitate is filtered off and dried to. give a mixture of diastereoraers of the title compound. -X- 7 0 10 0 1 EXAMPLE 19 <L.D) CB2C6Hs ?H3 -k 1 * . .CH CHNHCH CO NHCHCOOH 3 | (L) 0=P—OH I OH (1L) -1-amino ethyl phosphonic acid (see U.S. Patent Specification 4016148) is dissolved in anhydrous methanol 5 and an equimolar quantity Of thi'onvl chloride is added o thereto a drop at a time," the "solution being kept at 0 C. during the addition. After the addition is completed the resulting solution is allowed to varm to room temperature and stood at this temperature for from 6 to 8 hours. Vola-/o tiles are then removed under reduced pressure at room temperature to yield crude (1—L)—1—aminoethyl phosphonic dimethyl-.ester hydrochloride. A solution is made up of the dimethyl ester and an equi— molar quantity of sodium phenyl pyruvate in methanol £|nd is /5 adjusted to a pH in the range of 6.5 to 7 with IN NaOH solution and treated with a 50% molar excess of sodium cyanoborohydride. The reaction mixture is stirred for 2 days at room temperature, then' poured into water. The pH of the "resulting aqueous mixture is then adjusted to a -2D value in the "range- 2 to 3, and the resulting precipitate extracted with ethyl" acetate. The extracts are washed with water and dried. Evaporation of the solvent gives the crude mono-acid of formula: <jH2C6H5 CH —— CH NHCH CO„H 3 I 2 O-P. / \ HeO OMe </div>

Claims

<div class="application article clearfix printTableText" id="claims">



GO - - 

20100 1 

The mono-acid is dissolved in dimethylformamide together with an equivalent (with respect to the mono-acid) of L-alanine methyl ester hydrochloride, and one equivalent (with respect to the mono-acid) of N-ethylmorpholine. The resul-5 ting mixture is cooled to approximately 0°C. and one equivalent (with respect to the- jnono-acid) "of N-(3—dimethyl— aminopropyl)— N' -ethylcarbodiimide hydrochloride and 1 equivalent of N-ethylmorpholine and di-methylformamide is added thereto. 

The reaction mixture is allowed to warm to room temperature IO and stirred overnight. It 'is then poured into water and the precipitated product extracted with ethyl acetate. The extracts are washed with 0.5% wt/vol HCl, then with saturated sodium bicarbonate solution, dried and evaporated to yield a compound of the formula: 

CH2C6H5 CH 

II 

/O CH3 CH NH-— CH CO NHCHCOOCH3 

0=P OCH-, 

I 

0CH3 

This product -j_s dissolved in methanol,- and to the resulting solution is added, drop by drop, 3.1 equivalents with respect thereto of sodium hydroxide in the form of a IN solution. After stirring overnight at room temperature ■2.O the reaction jnixture is ' concentrated under reduced pressure, diluted with water and adjusted to pH>. in the "range 3 to 4 with IN HCl solution. 

The precipitated products are filtered, washed with water and dried to give a mixture of diastereomers of the title ZLS compound. 

-Gi - 

2 010 

WHAT//WE CLAIM IS. 

3- A compound having the formula: 

R 

3 

1 

HC 

K >: CON CK-( C) • 

i y 

R 

9 

K 

2 

I 

and the pharmaceutically acceptable salts thereof, in which 

R1 -is hydrogen; alkyl; halogen- 

loweralkyl; hydroxy-lower-alkyl ; lowerslkoxy-1 oweralkyl ; aryloxy-loweralkyl; amino-loweralky1; loweralkylamino-loweralkyl; di-loweralky1 aminoloweralkyl; acylamino-loweralkyl; diarylajninoloweralkyl; arylamino-loweralkyl ; guaniaino loweralkyl; heteroaryl; aryl; aralkyl; mer-Ccpto-loweralkyl; arylthio-loweralkyl; loweralkylaralkyl elkylthio loweralkyl; aralkyloxyalkyl; aralkylthio-alkyl or heteroaryloxvalkylwherein the latter 3 radicals may be substituted with halogen, loweralkyl, loweralkoxy hydroxy, amino, aminomethyl, carboxyl, cyano and/or sul-farnoyl; or alkenyl substituted by a heterocyclic group or alkyl sub stituted by a heterocyclic group, the latter two heterocyclic groups optionally being substituted by one or more groups chosen from loweralkyl, hydroxy, loweralkoxy amino, loweralkylamino, di-loweralkylamino, acylamino, halogeno, halogenoloweralkyl, cyano and/or sulfonamioo; 

- 62. - 

201001 

K2 is -COOK, COO-loweralkyl, COO-aryl-low^ralkyl, -COO-aryl, ° Ron 

" / • T, A 

-COO-CH -O-C-lower alkylor-CON^ wherein R2Q and 

R2 1 

are the same or different and ere selected from ■i,' hydrogen, loweralkyl, aryl.or aralkyl, or R2q anc^ R21 taken together form a saturated 5-? membered ring which can also contain oxygen as a ring heteroatom, or the group 

° f °R10 wherein 

R11 

10 is hydrogen, lower-alky1 or benzyl; and 

R 

11 is hydroxy, alkoxy, benzyloxy, loweralkyl, aryl or benzyl; 

R^ is hydrogen cr loweralkyl; 

R. (CH ) R. 

| 4 j 2 q 4 

X is -CH- or -N- 

wherein q is 0 or 1; 

R^ is chosen from the groups defined for R^, 

inaolyl , indolylelkyl, 

arninomethyl-phenylloweralkyl, 3-thianaphthenyl:raethyl and tetrahydronaphthyl methyl; Rj. is : hydrogen or loweralkyl;,; 

y;,is zero .or ;an integer -f rom 1 to 3; 

R^, and Rg-are chosen from the groups defined for R, ; ! and 

4 J 

Rg is chosen from the groups defined for R^, and when y is 2 or 3, R^ ana Rg can be on the same or a different carbon atom, 

201001 

subject to the proviso' that vhen X is -CH-,y=0, and Ris not ^-^en one or more of the following conditions 

11 applies: 

e) is pyrid}'3, thienyl, furanyl, naphthyl lower alkyl, 

naphthyl or aralkylthio; 

b) is Jovere]}:yJ; 

c) is fury"!methyl, |cyclo lower alkyl, aryl lower alkyl, thienylmethyl, tetrahydronaphthyl-methyl; 1- or 2-naphthyl-methyl, 3-thianaphthenyl-methyl, cycloloweralkylmethyl, loweralkoxylower-alkyl, aralkoxy loweralkyl, aryl, substituted aryl in which the substituents are one or more of: halogen, loweralkyl, hydroxyl, loweralkoxy, haloloweralkyl, nitro, mono-or diloweralkylamino, or cyano, and substituted aryl methyl substituted on the aryl moiety, by one or more of the aryl substituents defined in this proviso with the exception of hydroxyl; 

a) R^ is acylarninoloweralkyl, mono-or di-loweralkylamino loweralkyl or. one of the"groups mentioned above (in (c))for excluding phenyl. 

- 64 - 

201001
2. A compound as defined in Claim 1, in which
R
4 

X is - CH and is hydrogen, substituted or unsubstituted aryl, heteroaryl where the heteroatom is 0, S, or N, and substituted or unsubstituted lower-alky! wherein the substituents on the substituted lower—alkyl __ 

can be a halogen atoms, one or more of substituted or , unsubstituted aryl, heteroaryl where the heteroatom is 0, S, or N, substituted or unsubstituted arylthio, amino, 1owera 1kanoy1 - amino, mono and di-lower alkyl-ami no, substituted or unsubstituted aryloxy, or substituted or unsubstituted aralkylthio; in vhich the substituents on the substituted ar.yl groups or jnoieties t can be: I 

halogai atom, loweralkyl, hydroxyl,—loweralkoxy- halo- 

lower alkyl, nitro, mono—or diloweralkylamino, or cyano; 

I I ... . , 

R2 is 0=P-0R10> carboxy, -COO-loweralkyl, -COO-aryl, 

R11 " 

i 

-COO-aryl-lower alkyl wherein the aryl or aryl moiety of the aryl- j 

0 

lower alkyl group can be substituted as in Rj, -COO- CH2 - 0 - C - . 1 loweralkyl, ! 

wherein 

- GS — 

201001 

R20 and ar^ the same or different and are selected from hydrogen, loweralkyl, unsubstituted or substituted aryl wherein the substituents are as defined in R^ in this claim, unsubstituted or substituted aralkyl wherein the substituents are on the aryl moiety and are as defined in R^ in this claim; or R^q and R2^ together with the nitrogen form a 5-7 membered Saturated ring which can also contain oxygen as part of the ring; 

is hydrogen, f u rylmethyl thienylmethyl , tetrahydro- 

nephthylmethyl, 1- or 2-naphthylmethyl , 3-thia-naphtheny1 methy1, loweralkyl, cyc1o1owera1ky1, cyclo-1 oweralkylmethyl, hydroxyloweralkyl , acy 1 ami no-1ower -alkyl, ami no-1oweralky1, mono- or di-1owera 1ky1 ami no -loweralkyl, 1owera1koxyloweralkyl, ara 1|<oxylower— 

alkyl wherein the aryl moiety can be substituted as defined in R " in this claim, 3-indolylloweralkyl, aralkyl, 

I " ~ ! "t a^yl/ jsubstituted ^^al^yljand substituted aryl jwherein substituents are as defined for aryl substituents in R^/" 

R^, R^ and Rg are chosen from the groups defined for in this claim; and 

Rg is chosen from the groups defined for R^ in this claim o 

and a pharmaceutically acceptable salt thereof. 

- 

201001 

A compound as defined in Claim 2, in vhi ch is 1, 2, or 

3, R^ is aryl 1 oweral ;.yl, R^ is carboxyl, -COO-loverallcyl, 

or -COO-arylloveralkyl, R0 is hydrogen, R. is benzyl, 1- 

5 3 

or 2-naphthylmethyl, Icverallcyl, substituted or unsubstituted phenyl-loweralLyl or 2- or 3- thienylmethyl,R R , 

5 6 

R7 and Rg are hydrogen, and Rg is carboxyl, or, 

R 

20 

-CON in vhich one of R and R 

\ 20 21 

R 

21 

is hydrogen and the other is loweralkyl, or together with the nitrooen atom to which they are attached R and R • 

. 20 21 

form a 5-7 membered saturated ring containing oxygen as a ring heteroatom; or a pharmaceutically acceptable salt thereof. 

A compound as defined in Claim 3 , wherein y is 1, 

tdi | 

R^ is 1-naphthylmethyl, para- tolyumLhyl, benzyl or phenylethyl, 

' ' ' 1 

R_ is carboxy, and R. is para-toly methyl, benzyl,cor a pharmaceutically 

! 

acceptable salt thereof. I 

The compound N^L);-(1-carboxy-3-phenylpropyl) - (L)-ptenylalanyl-^-alanine, or 

N - (L) - (l-carboxy-2-phenylethyl) -(L) -phenylalanyl-j3_alan±ne. 

- 67 - 

201004 

A compound according to Claim 1, in which y is zero, 

/ 

R is as defined in Claim 1, 

i 

R^ is 0=P—ORio 

R11 

R3' R4' R5' R6' R7' R8' R10 and Rn and x are as defined in Claim l.and-r9 is carboxyl. and the pharmaceutically acceptable salts thereof v*77 Xmethoa of preparing a compound of formula 1, which is optionally ^protected by a. suitable protecting group(s), as defined in Claim 1, which is characterised in that the compound is prepared by an appropriate method selected from the following methods (wherein in the following formulae R^, R p , ■ R ^ , R ^ , R^> ^ 5 > ^ 7 ». . ? g -and Rg and y are as defined in Claim 1), 1;a) Reducing a compound of the formula A at the C-N doublebond;R7;R, C = N X CON— CH— (C ) Rq ► I;I I I i Y;R2 R
5 R6 R8;A;for the production of a compound of formula 1 in;1;which R^ is hydrogen and R2 is other than O=P-^OR10;;R11;-68 -;201001;Couplinq a compound of formula A' with a compound of tne formula B1 R R;l7 l3;H NCH (C) Rn + R- CH— N— X — COOH;t | i 9 I;R6 R8 R2 1 1;A1 B";Reducing a compound of the formula X at the C=N double bond;H R, R r R-?;l I I5 i7;R C — N = C— CON CH — (C) Rg * I 

1 ' y 

R2 R
6 R8 

£ X 

for the production of a compound of formula 3 in which R^ is hydrogen; 

-69 - 

201001 

d) Alkylating an amine of formula S' with a compound of formula 7 ' 

R R R 

I5 l
7 I1 

•N X CON CH—(C) Rn -t Hal — CH ^ j u^ 1 1 y 9 i 

H PR R 

6 8 2 

S" T' 

in which Hal represents halogen;, and e) for the preparation of compounds in which. is hydrogen 

O l» 

and R_ is -P-QR,_ , 

^ I X U / 

R11 

reacting a compound of formula A" with a phosphite ester or phosphonate ester of formula Z I r-7 0 

I J 7 „ 

R — CH=N-X-CONHCH- (C) - R_ + H-P—OR.. n ; 1 | i y 9 j 10 

R6 R8 R11 

A" 1 Z 

followed by the removal of any protecting groups and thereafter, if desired, converting the resulting compound of formula 1 into another compound of formula I and/or forming a salt thereof, and if desired isolating a preferred isomer. j
8. A compound having the formula I j(as herein defined) substantially as hereinbefore described with reference to the examples.
9. A method of preparing a compound of formula X as hereinbefore defined substantially as hereinbefore described with reference to the examples. DATED THIS^^DAY OF 

A. J. PAHK & SON 

AGENTS FOR THE APPLICANTS 



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