CA1220477A - Amide derivatives as histamine h-2 receptor antagonists - Google Patents

Abstract

"Amide Derivatives as Histamine H-2 Receptor Antagonists"

The invention relates to amide derivatives which are histamine H-2 antagonists and which inhibit gastric acid secretion. According to the invention there is provided a guanidine derivative of the formula I:- I
in which R1 is a hydrogen or 1-10C alkyl, 3-8C cycloalkyl, 4-14C cycloalkylalkyl, 3-6C alkenyl, 3-6C alkynyl, 1-6C alkanoyl, 6-10C aryl, 7-11C aralkyl or 7-11C aroyl, the aryl, aralkyl and aroyl radical being optionally substituted; ring X is a heterocyclic ring as defined in the specification; A is phenylene or 5-7C cycloalkylene, or a 1-8C alkylene into which is optionally inserted one or two groups; D is O or S; and R2 and R3 are hydrogen or a variety of radicals described in the specification:
and the pharmaceutically-acceptable acid-addition salts thereof. Manufacturing processes and pharmaceutical compositions are also described.

Description

~2~

- l - 31723A

This application is a division of Serial No.
397,033 filed February 25, 1982.
This invention relates to amide derivatives which are histamine H-2 antagonists and which inhibit gastric acid secretion.
It is postulated that the physiologically-active compound histamine, which occurs naturally within the animal body, is able to combine, in the course of exerting its activity, with certain specific receptors of which thexe are at least two distinct and separate types. The first has been named the H~l receptor (Ash and Schild, Brit.J.Pharmac. 1966, 27, 427) and the reaction of histamine at this receptor is blocked (antagonisedl by classical "antihistamine" drugs such as mepyramine. The second histamine receptor has been named the H-2 receptor (Black et al., Nature, 1972, 236, 385) and the action of histamine at this receptor is blocked by drugs such as Cimetidine. It is known that one of the results of the blockade of the action of histamine at the ~-2 receptor is the inhibition of the secretion of gastric acid and a compound which possesses this ability is there~ore useful in the treatment of peptic ulcers and other conditions caused or exacerbated by gastric acidity.
` In ~K Patent Application No. GB2052478A and Japanese Patent Application No. J56108777(Derwent Accession No. 74736 D/41) there are described histamine H-2 receptor antagonists which are 2-guanidinothiazole derivatives carrying a side chain in the 4-positiorl to the end of which is attached a carbamoyl group.
It has now been discovered that certain other heterocycles carrying both an optionally-substituted guanidine group and a side chain to the end of which is ; attached an optionally substituted carbamoyl group are ~_ potent histamine H 2 receptor antagonists. ~y

- 2 -According to t~e invention there is provided a guanidine derivative of the formula I:-RI N H
\C=I`~ X ;,~ c - ~1~ R3 in which Rl tS a hydrogen atom or a l-lOC ~lkyl,

3-8C cycloalkyl, 4-14C cycloalkylalkyl, 3-6C alkenyl, 3-6C alkynyl, 1-6C alkanoyl, S-lOC aryl, 7-llC aralkyl or 7-llC aroyl radical, the aryll aralkyl and aroyl radicals being optionally substituted on the aryl ring by one or two substituents selected from halogen atoms and 1-6C alkyl, 1 6C alkoxy, 1-6C alkylthio, trifluoro-methyl, hydroxy and amino radicals;
in ring X the dotted line is a double bond on one side of the nitrogen ato~ and Z is a carbon or nitrogen atom such that ring X is a 5- or 6- membered aromatic hetero-cyclic ring which contains at least one nitrogen-atom and may optionally contain one or two additional hetero atoms selected from oxygen, nitrogen and sulphur atoms, which heterocyclic rin~ may, where possible, carry one or two optional substituents, the optional substituents on ring X being selected from fluorine~ chlorine and bromine atoms and 1-6C alkyl, 1-6C alkoxy, trifluoro-methyl, hydroxy and amino radicals;
A:is a phenylene or 5-7C cycloalkylene radical or a 1-8C
- alkylene chain which is optionally substituted by one or two 1-3C alkyl radicals and into which is optionally : inserted, as part of the backbone of the chain, one or ; two groups selected from oxygen and sulphur atoms and NH, 1-6C N~alkylt cis and trans vinylene, ethynylene, phenylene and 5-7C cycloalkylene radicals, provided that the shortest link bet~een ring X and C=D is of at least 3 atoms, provided that when an optional insertion ~ 7 is made in chain A which results in the inserted group being directly attached to C=V the inserted group is other than an oxygen or sulphur atom or an NH ~r N-alkyl.
radical, and provided that no two insertions selected from oxygen and sulphur atoms and NH and N-alkyl radicals are directly attached one to the other;
D is an oxygen or sulphur atom;
R2 is a hydrog~n atom or a hydroxy, amino, 1-6C alkyl-amino, 1 6C haloalkylamino, 1-6C alkanoylamino, 1-6C
alkyl, 3-8C cycloalkyl, 4-12C cycloalkylalkyl, 2-6C
alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 1-6C alkoxy, 1-6C hydroxyalkyl, 2-lOC alkoxyalkyl, 2-lOC alkylthio-alkyl, 1-6C aminoalkyl, 2-8C alkylaminoalkyl, 3-12C
dialkylaminoalkyl, 2-8C alkanoylaminoalkyl, 8-14C
aroylaminoalkyl, 3-lOC al~oxycarbonylalkyl, 2-8C carbamoyl-alkyl, 6-lOC aryl, 7-llC arylalkyl, heteroaryl or hetero-arylalkyl radicals, wherein the heteroaryl part is a heterocyclic aromatic ring containing one, two or three heteroatoms selected ~rom oxygen, nitrogen and sulphur atoms, wherein the alkyl part of the heteroarylalkyl radical is 1-6C and wherein, when R3 is or contains an aryl or heteroaryl ring, that ring is optionally substituted by one ox two groups selected from fluorine, chlorine, bromine and iodine atoms and 1-6C alkyl, 1-6C
alkoxy, 1-6C alkylthio, 2-6C dialkylamino, 2-6C alkanoyl, 'rifluoromethylJ hydroxy and amino radicals;
R3 is a hydrogen ato~ or R2 and R3 are joined to form, together with the nitrogen atom to which they are ttached, a 5-, 6- or 7-membered saturated ring which . 30 optionally contains a double bond or an additional oxygen atom, NH or 1-6C N-alkyl radical;
provided thak when Rl is a hydrogen atom or an alkyl radical, ring X is a thiazole ring in which A is attached at the 4-position and A is an alkylene chain which has a single optional insertion oE a sulphur atom, then NR2R3 is other than NH2 r NHOH or NH alkyl:
, and the pharmaceuticaly~acceptable acid-addition salts thereof.
It is to be understood that, in the above formula I and throuqhout this specification, although the double bond in the guanidine residue attached to ring X has been inserted in a particular position, other tautomeric forms are possible, and this invention includes such tautomeric forms within its scope, both in terms of the compounds of the invention and in terms of the manufacturing processes. It is alco to be understood that when A ~s or contains a cycloalkylene radical the groups attached to this radical may be in the cis or _rans configuration. When A is or contains a cycloalkylene radical and~or when A is an alkylene chain substituted by one or two alkyl radicals the compound of the formula I will, in most instances, contain at least one asymmetr~c centre. In such cases the compound of the formula I will therefore exist in at least two enantiomeric forms, the prec;se number being determined by the number of asymmetric centres. The biolo~ical activity, as hereinafter defined, of these enantiomeric forms may differ, and it is therefore to be understood that this invention encompasses the racemate of the formula I, including any possible diastereoisomeric forms, and any enantiomeric form w~ich po sesses the disclosed biological activity, it being a matter of common general knowledge to one skilled in the art how to separate - diastereoisomeric forms and how to separate a racemate into its enantiomers and determine the biological activity of each.
A particular value for Rl is a hydrogen atom or a methyl, ethyl, propyl, isopropyl, butyl, cyclohexyl, cyclohexylmethyl, allyl, propargyl, acetyl, phenyl, benzyl or benzoyl radical, the phenyl, benzyl and benzoyl radica~ being optionally substituted on the ~ 7~ 31723 benzene ring by one or two substituents selected from fluorine, chlorine and brom~ne atoms and methyl, methoxy, methylthio, trifluoromethyl, hydroxy and amino radicals.
A particular value for ring X is an oxazole, S thiazole, imidazole, 1,2,4-thiadiazole, 1 t 2,4-oxadiazole, 1,2,3-triazole, 1,2,4-triazole, pyrazole, pyra~ine, pyridine, pyrimidine or 1,3,5-triazine ring, each being optionally substituted, where possible, hy one or two substitutents selected from fluorine, chlorine and bromine atoms and methyl, methoxy, trifluoromethy7, hydroxy and amino radicals.
A particular value for -A- is a phenylene, cyclopentylene, cyclohexylene, trimethylene, tetra-methylene, pentamethylene, thioethylene, thiotri-methylene, thi.otetramethylene, thiopentamethylene,oxyethylene, oxytrimethylene, oxytetramethylene, methylenethiome~hylene, methylenethioethylene, methylenethiopropylene, methyleneoxymethylene, methylene-oxyethylene, ethyleneoxyethylene, oxy-2-methylethylene, ~opropylenethiomethylene, oxyethyleneoxymethylene, iminoethylene, iminopropylPne, vinylenepropylene, oxymethylenevinylene, 1,3-phenylene, 1,3-cyclopentylene, methylene-1,4-phenylene, ethyleneoxymethylene-1,4-phenylene, oxy-1,3-phenylenemethylene or thiomethylene-e~nylenemethylene radical. These values for -A- are written reading from left to right in formula I such that the first named part of the radical is attached _ ~s ~ing X and the last named part of the radical is attached to C=D. Thusj for example, when -A- is a methylenethioethylene radical,the compound of the ormula I contains the part structure II:-C ~X ,~Z--CH 2.~ c ~ ~c U ~ - c-- II

317~3 A particular ~alue for R is a hydrogen atom or a hydroxy, amino, methylamino, 2,2,2-triflu~oethyl-amino, acetylamino, methyl, cyclohexyl, cyclohexylmethyl, allyl, propargyl, 2,2,2-trifluoroethyl, methoxy, 2-hydroxyethyl; 2-methoxyethyl, 2,methylthioethyl, 2--aminoethyl, 2-methylaminoethyl, 2-dimethylaminoethyl, 2-acetylaminoethyl, 2-benzoylaminoethyl 7 methoxy~arbonyl-methyl, 2-carbamoylpropyl, phenyl~ benzyl, heteroaryl and heteroarylmethyl, ~n the latter two of which the heteroaryl part is a furan, thiophene, pyrrole, thiazole oxazole, imidazole, thiadiazole, oxadiazole, triazole pyrazole , pyridine or pyrimidine ring, and wherein when R2 is or contains a phenyl or heteroaryl ri.ng, that ring is optionally su~st~tuted by one or two groups selected from fluorine, chlorine, bromine and iodine atoms and m~thyl, methoxy, methylthio, dimethylamino, acetyl, trifluoromethyl, hydroxy and amino radicals.
A particular value for the ring formed when R2 and R3 are joined is a pyrrolidine, piperidine,.
morpholine, piperazine or.N-methylpiperazine ring.
The ~ollowing are 7 preferred ~eatures of the guanidine derivati~e of the formula I. When any one of these features is taken, either singly or in combination, with the other general or particul~r features of the guanidine derivati~e of the formula I
listed above,there are obtained preferred sub-groups of compounds within the above general definition.
~ 1. R2 and R3 are hydrogen atoms.
2, Rl is a methyl, ethyl, propyl, isopropyl.
or a~lyl radical.
3. Ring X carries no optional substituent.

4, Ring X is a pyrazole, pyridine, pyrimidine in ~hich A is attached at the 2-position, or 1,2,3-triazole ring.

5. Ring X is a pyrimidine in which A is attached at the 2-position or pyridine ring and A is a thio-!

~&~ r trimethylene or tetramethylene radical.

6. Ring X is a pyrazole or 1,2,3-tr~ zole ~ ring and A is a tetramethylene radical.

7. D is an oxygen atorn.
Specific compounds of the invention are set out in the Examples. The following is a group of preferred compounds:
(4-[2-propylguanidino3pyrimid-2-ylthio)butyramide (Example l);
4-(4-12-methylguanidinolpyrimid 2-ylthio)butyramide ~Example 3);
4-(4-[2-isopropylguanidino~pyrimid-2-ylthio)butyramide tExample 4);
4-(6-12-propylguanidino]pyrid-2-ylthio)butyramide (Example 7~;
5 (4-t2-allylguanidinol-1,2,3-triazol-2-yl~valeramiae (Example 8), 5-'4-[2-propylguanidino~-1,2,3~triazol-2-yl)valeramide (Example 9~;
5-(3-[2-propylguanidino]pyrazol-1-yl3valeramide (Example 10~;
and the pharmaceutically-acceptable acid-addition salts thereof.
A suitable pharmaceutically-acceptable acid-addition salt of the guanidine derivative of the formula 1 is, for example, a salt formed with hydrochloric, hydrobromic, phosphoric, sulphuric, acetic, citric or _ maleic acid.
~ The guanidine derivative of the invention may be manufactured by methods in which the actual chemical reactions involved are known in themselves. ~he following processes, Rl, R2, R3, A, D and ring X
having the meanings stated above, unless indicated otherwise, are therefore provlded as further features of the invention.

The process of the invention is characterised by:~ j ~a) reaction of a compound of the formul~ III:-C~ ~ -~ X ~ ~ - C~ ~ III
H~

or an activated derivative thereof with a compound of the formula R2R3NH. The activated derivative may, for example7be an ester, for example a 1-6C alkyl ester for example a methyl or ethyl ester, or an acid halide, ~or example an acid chlortde or acid bromide.
Altexnatively the activated derivative may be an anhydride~ for example a mixed anhydride. Particularly useful mixed anhydrides are those ~ormed by reaction of the compound of the formula ~Iwith a chloroformate, for example ethyl chloroormate or isobutyl chloroformate.
The reaction may be conducted in a diluent or solvent such as methanol, ethanol, methylene dichloride, tetra-hydrofuran or dimethylformamide and the reaction may be accelerated or completed by the application of heat, for example by heating to the boiling point of the diluent or solvent. When the activated derivative is an acid halide it is advantageous to cond~ct the reaction in the presence of a base such as triethylamine and to use - a non-alcoholic diluent or solvent.
(b) for those compounds in which R2 and R3 are hydrogen atoms and D is an oxygen atom, hydrolysis of a compound of the formula IV:-~Z~fl~7~7 g Ri NH ~--~
~ C = ~ -C, X ,Z ~ IV

The hydrolysis is preferably carried out by use of a strong mineral acid such as concentrated sulphuric acid or by use o hydrogen peroxide in a basic medium, for example in the presence of sodium hydroxide. When Rl is a hydrogen atom, an acid labile protecting group attached to the nitrogen atom, for example a t-butyl radical, may also be removed during this pocess.
(c) construction of the guanidine radical attached to ring X by reaction of the appropriate thiourea, or a 1-6C S-alkyl (e.g. S-methyl~ or S-benzyl derivative thereof, or a salt of such a derivative, with the appropriate amine. The guanidine radical in the compound of the formula I contains three nitrogen atoms each of which carries different substituents. The appropriate amine for use in this reaction may thereEore be ammonia~ an amine of the formula RlNH2 or an amine of the formula:-~ ~ ~ D
H2~1- c >C ~ --A--C ~R2~3 v 2~ The reaction may be conducted us~ng an excess of one of the reactants as a diluent or solvent, or an additional diluent or solvent, for example methanol or ethanol, may be added. In many ca~es it is advantageous to use a catalyst such as mercuric oxide, lead oxide or sodium hypochlorite. The reaction may be conducted at ambient temperature or it may be accelerated or completed hy the application of heat, for example by heati~g to the ~boiling point of the diluent or solvent.
(d) for those compounds in which Rl is a 3-lOC
alkyl radical, hydrogenation o the corresponding unsaturated derivative. In such an unsaturated derivative the radical corresponding to R1 will have the same number and arrangement of carbon atoms as Rl and will contain one or~ where possible, more dou~le and/or triple bonds. The reaction may be conducted in a diluent or solvent such as ethanol and in the presence of a catalyst such as a palladium on charcoal catalyst.
(e) construction of the guanidine :-adical attached to ring X by reaction of the appropriate cyanamide with the appropriate amine. Since the guanidine radical in the compound of the formula I contains only one unsubstit~ted nitrogen atom there are two appropriate amines, namely the amine of the formula RlNH2 or of the for~ula Y given above.
(f~ for those compounds in which the group inserted into A i~ an oxygen or sulphur atom or an NH or N-alkyl radical, reaction of a compound of the formula VI or VI~:-RINU ~ ~f ~\
25~ ~ C~ ~ Z ~ H

~ ~C=~ ~--A'- R4 VI~

with a compound of the formula VIII or IX respecti~ely:-.
~ - ~ C ~ ~ ~3 VIII

~ A - C - ~ / 3 IX
R

in which G is an oxygen or sulphur atom or an NH or M-alkyl radical, R4 is a displaceable radical and Al and A2 are fragments of A, including direct bonds, and are such that Al-G-A2 alls within the definition of A given above. R4 is, for example, a halogen atom, for example a chlorine, bromine or iodine atom. When R4 is directly attached to ring X R4 may, for example, be a methyl-sulphinyl or methylsulphonyl radical.
(g) for those compou~ds in which Z is a nitrogen atom, reaction of a compound of the formula X:-H2~ /~ I`J C~X/ 1~ H x _ 15 with a compound of the formula XI:-R4--A--c~ ~R3 XI

in which R4 is a displaceable radical. R4 is, fore~ample, a halogen atom, for example a chlorine, hromine or iodine atom.

~ 12 - -(h~ fcr those compounds in which r:ing X is a thiazole ring, reaction of a compound of the f~rmula.
XII:-Rl~ S
C ~ C ~æ XII

5 with a compound of the formula XIII:-1H--~O--~--C ~ R3 XIII

in which Hal is a chlorine or bromine atom and R5 is a hydrogen atom or the optional substituent on the thiazole ring. The reactlon may be conducted in a diluent or solvent such as acetone and may be accelerated or comp-leted by the application of heat F for example by heating to the boiling point of the diluent or solvent.
When the process of the invention manufactures the compound of the fo~mula I in the form of the free base and an acid-addition salt is required, the compound of the formula I in the free base form is reacted with an acid ~hich affords a pharmaceutically-acceptable anion.
. .
The starting material of the formula III for ~e in process (a3 may be obtained by separate construction of the two side chains on the appropriate ring X. Thus ~ th^ left-hand side chain may be constructed by reduction of a nitro group to an amino group, reaction of this amino group with an isothiocyanate of the formula Rl- N=C=S, and finally reaction of the resulting thiouxea.with aT~monia in the p~esence of mercuric oxide. The method of construction of the right hand side chain may vary depending on the nature of ~ing X, the nature of the atom in ring X

~2'~ 7 - 13 - .

to which A is attached (caxhon or nitrogen~ and the presence or absence of inserted atoms or groups in chain - A. In this construction it may be necessary to protect the acid function as a cyano or ester group and to hydrolyse to the acid as a final step. When A contains no inserted group or the inserted group is a phenylene radical and Z is a carbon atom, it is preferable to construct the ring X with the right hand chain already in place. Thus when ring X is a thiazole ring a process similar to that described in process ~h) may be used, for example as illustrated in Examples 13 and 17. When rin~ X is a 1,2,3-triazole ring, it may be formed by reaction of methazonic acid with a suitable azide. When ring X is a pyrimidine ring, it my be formed by reaction of a suitably substituted amidine with 2-chloroacrylo-nitrile, or example as illustrated in Example 2. When the inserted group in A lsa vinylene or ethynylene radical, A may be introduced by formation of the double or triple bond by standard coupling methods. When the inserted yroup in A is a cycloa~kylene radical, the chain A may be constructed by a conjugate addition to the corresponding cycloalk-2-enone. When the inserted group in A is an oxygen or sulphur atom or an NH or N-alkyl radical, the xight hand chain may be built up by a method similar to that described in process (f), for example as illustrated ln Examples 1, 6, 15 and 1~.
When Z is a nitrogen atom, the right hand chain may be formed by a method similar to that described in process ~g), for example as illustrated in Examples 8 and 10~
The starting material of the formula IV for use in process (b) may be prepared by methods exactly analogous to the methods of preparation of the compound of the formula III. Indeed, as already explained, the compound of the formula ~V may be an imrnediate precursor of the compound of the formula III.

~ 7~ 311~

The s~arting material of the formula ~
for use in process ~c1 may be prepared by the methods described a~ove for the preparation of the compounds of the formula III or IV in w~ich the right hand chain is constructed first, ~ollowed by use of one of the processes (a~ or ~b).
The cyanamide~ corresponaing to the amine of the formula V, for use in process (e~ may be prepared by reaction of the compound of the formula V with cyanogen bromide.
The starting materials of the formulae VI
and VII for use in process (f), and of the formula X
for use in process (g) may be prepared by construction of the guanidine chain on a suitably substituted ring X.
The starting material of the formula III for use in process ~a) i~ a part~cularly useful intermediate for preparing the compounds o~ the ~ormula I. This starting material, and the activated derivati~es (l-6C
alkyl ester, acid chloride, acid bromide, mixed anhydride) thereof are therefore provided as a further featu~e of this invention. Particularly useful mixed anhydrides are 3~ 77 !

-- 1 5 -- ~ I

those formed with 1-6C alkyl chloroformates, for example ethyl and isobutyl chloroformates.
The starting material of the formula IV for - use in process (~) is a particularly useful intermediate for preparing the compounds of the formula I. This starting material is therefore provi~ed as a further feature of the invention.
As noted above, the guanidine deriva~ive o the invention is a histamine H-2 antagonist, inhibits-the secretion of gastric a~d in warm-blvoded animals and is th~refore useful in the treatment o~ peptic ulcers and other conditions caused or exacer~ated by gastric acidity, including stress ulcers and gastrointestinal bleecling due to trauma.
lS The histamine ~-2 anta~onist activity may be demonstrated on standard tests, for example by the ability of the cQmpound of the formula I to inhibit the histamine-induced positive chronotropic résponse in the spontaneously beating right atrium of the guinea pig or by its ability to inhibit the histamine-induced uptake of aminopyrine into the acid space of pzrietal cells.
The guinea pi~ atrium test is carried out as ~ollows:-A guinea pig right atrium is suspended at 1 g.
tension (is~metric) in a thermostatically~controlled(30C) tissue bath (25 ml.) containing oxygenated (95% 2~5% C02) Krebs-Henseleit buffer (pH 7.4). The tissue is allowed to stabilise over 1 hour during which time it is washed 2~4 times. Individual contractions - 30 are recorded with a force-displacement transducer through a strain gauge coupler, and instantaneous rates are monitored with a cardiotachometer. A control response to 1 ~M histamine is obtained after which the tissue is washPd 3 times and allowed to re-equilibrate to basal rate. After re-equilibration for 15 minutes, the test compound is added to the desired final concentration.

Ten minutes after addition of the compound histamine (1 ~M) is again added and the response ~o histamine in the presence of antagonist is cQmpared to the ~histamine control response. The result is expressed as a percentaye of the histamine control response.
Thereafter the apparent dissociation constant of the H-2 antaqonist is determined by standard procedules.
The ~minopyrine test is carried out as follows:-Gastric mucosa frQm the New Zealand white rabbit is removed frQm the underlying muscle and washed in Buffer 1 lcontaining per litre NaCl;(8.007 g.), KCl (0.201 g.), Na2HP04 (0.113 g.), KH2PO~ (0.204 g.), CaC12.2H20 (0.132 g.~, MgC12 (0.101 g.) and glucose (1 g.), adjusted to pH 7.4 ~ith NaOH]. Ihe tissue is finely chopped, su~ded ln Buffer 1 and washed three times with Buffer 1~ The tissue is then suspended in dispersion medium lcollagenase (Sigma Chemical Co., Type V; 100 mg.~ and bovine ~erum albumin (Miles Laboratories Ltd., Fraction V; 100 mg.) in Buffer 1 (100 ml.); 50 ~1. per 10 g. net weight of tissue] and incubated at 30 & and pH 7.4 (maintained by continuous monitoring) with stirring under an oxygen atmosphere. After 30 minutes the tissue is allowed to settle and the supernatant liquid is removed.
Fresh dispersion medium (50 ml. per 10 g. wet weight of tissue) is added and incubation is continued with the tissue being largely dispersed into glands and whole ce~ls after 40-60 minutes. Any remaining lar~e pieces of tissue are removed by filtration through nylon mesh.
The mLxture of glands and cells is collected by centri-- 30 rugation at 200 x g. and suspendecl in ~uffer 1 containing 1~ bovine serum albumin (Miles Laboratories Ltd., Fraction V). Finally the cells and glands are washed 3 times with Buffer 1 and suspended in Buffer 2 lcontaining Eagles MEM
(500 ml.), Aprotinin*(Sigma Chemical Co., 10 mg.) ancl HEPES ~2-l4-(2-hydroxyethyl)piperazin~l-yl]ethanesulphonic acid; 150 J~, 20 ml.) adjusted to pH 7.4 with NaOli;
* Reg. TM

- 17 ~

150 ml. p~r 10 g. ~et weight of tissue]. The tissue suspension is stirred under an o~ygen atmosphere at 32C
for at least 1 hour before use. The tissue suspension is incubated with the test compound and ~ninopyrine ~10 ~M~
labelled with C on ~he dimethylamino group ~0.1 ~Ci/ml.) for 20 minutes. The uptake of the ~minopyrine is then stimulated by addition of histamine and the phospho-diesterase inhibitor ICI 63197 (Eiochem.Soc. ~
_ublication 1,~1973, pp 127-132~ to final concentrations of 10 ~. and 5 x 10 M. respectiYely. After 18 minutes the cells~glands are separated from the incubation medium by filtration of the suspension through glass microfibre filters. The cells/glands are quickly I ~ 10 seconds) washed three tLmes with ice-cold Buffer 1. The C 4 aminopyrine retained by the tissue is measured on a scintillation counter and the degree of inhibition of upta~e by the test compound is cal~ulated by reference to a control sample. The concentration of test cQmpound giving 50~ inhibition is then calculat~d graphically rom a series of tests run at differe~t concentrations.
All the compounds exemplified in this spec-ification were tested either on the ~uinea pi~ atrium test or on the aminopyrine test. All those tested on the guinea pig atrium test are active at or ~elow a bath concentration of 10 ~M. and the more active c pounds show complete inhibition of response at this concen-tr~tion. All those tested on the ~minopyrine test gave a 50% inhibition of uptake of aminopyrine at or below a concentration of 3 ~M
The inhibition of the secxetion of gastric acid may be demonstrated in standard tests, for example by the ability of the compound of the formula I, when dosed intra~enously, intragastrically or orally, to inhi~it the secretion of acidic gastric juice in, for example, rats,or dogs provided with gastric fistulae or denerYated fundic pouches,and whose gastric secretion is stimulated by administration of a secretagogue, for 7~

example histamine, pentagastrin~ bethanechol or food.
TAe test in rats is carried out as follows:-Female rats (200-230 g.) are anesthetized by intraruscular administration of urethane (1.5 g/kg.~
and th~ trachea cannulated. A soft tube is passed down tne oesopna~us into the stomach and secured by a tie in the neck region. A ~ulti-orifice plastic tube (3 mm.
diameter) is passed into the antral region of the stomach, via an incision in the duodenum, and tied in place by means of a ligature around the pylorus. Saline (~.~1. NaCl) is per~usea through the stomach via the oesophageal cannula at a rate of 7 ml./minute and collected into beakers from the pyloric outlet over periods of 10 minutes.
Acid secretion is stimulated by subcutaneous administration of the specific ~-2 agonist dimaprit in a loading dose of 10 mg~Jkg. followed by an infusion of 30 mg./kg./hour.
~cid output is computed by titration of tlle 10 minute sam~les to an end point of pH 6.4 with 20 mM. NaOH. When secretion has reached a plateau (three consecutive readings within 5%) the test compound is administered intra~enously via a cannula placed in the left external jugular vein. Secretion is then measured for a ùrther 2 hours. A stock solution of each t~st compound is prepared (10 mg.Jml. in DMSO) and appropriate dilution made with saline to enable injection in a dose volume of 1 ml./kg. (DMSO <2%)-The test in dogs provided with chronic fistulae is carried out as follows:-A fe~ale pure bred beagle (9 12 kg.~ ha~ing a 3~ snronic gastric fistula is fasted overnignt with waterad lib. During tne experiment the dog is lightly restrained in a standing position. When studying the test compound by the intravenous route~ the fistula i~ opened and, after ascertainlng the absence of basal secretion over a period of 30 minutes~ a continuou~
intravenous infusion of secretagogue (0.5 ~mol,/k~/hour of histamine or 2~/k~O/hour pentagastrin) in saline -- 19 -- ~

(15 r.ll./hour) is begun. Gastric acid samples are collected every 15 minutes. The volwne of eac~, sa~ple is measured and a 1 ml. aliquot is titrated to neutrality with lOO~M NaO~ to determine acid concentration.
~nen a plateau of secretion is reacned (1-2 hours), tne test co;npound is a~ inistered intravenously in saline and gastric acid s~nples are collec~ed for a further 2-3 hours during which time the infusion of the secretagogue continues uninterrupted.
~hen studying ~he test compound by the intragastric route/ the aDsence of basal secretion over a period of 30 minutes is ascertained and the test compound, contained in 25 ml. o 0.5% w/v hydroxypropyl ~lethylcellulose and 0.1% w~v 'Tween' lS 80 in water ~'Tween' is a Trade Markl is instilled into the st~nach through a fistula dosing plug. ~ne hour later, the fistula is reopened and intravenous infusion of a secretagoyue, as described abo~e, is immediately begun. ~astric acid samples are measured as described above and the approach of acid secretion to a plateau is compared to that of a control animal which is dosed intragastrically only with the ~osing vehicle.
~hen studying the test compound by the oral route it is administered in a gelatin capsule with 15 ml. of water. One hour later~ the fistula is opened and intravenous infusion of the secretagogue is immediately begunD Gastric acid samples are measured as above and the approach of acid secretion to a plateau is compared to th`at of an undosed control animalO
The test in dogs provided with denervated fundic pouches i5 carried out as ollows;-Male beagle do~s (14-22 kg.) are prepared with vagally denervated pouches of the fundic gland area by the method of Rudick et al. (~.Sur~.~es. 1967, 7 383.) The animals are allowed 4-6 weeks to recover from surgery 7~ 1 - 20 ~

and a further period of 2-3 n~onths prior o routine use, to allow for table traininy and standardization of secretory responses. The dogs are star~ed for 23 hours before use (water _d li~ and during experiments they are lightly restrained in cloth slings. After rinsing the poucn with warn~-ater, histamine is infused subcutaneously at a rate of 10 ~g./minute. This dose of agonist produces a su~maximal (60-90~ of li.axLmum) increase in acid output in all dogs used. Pouch secxetions are collected over 15 minu~e periods int~ graduated glass test~tubes and the ~olume measured to the nearest O.1 ml.
A 500 ~1 sample is diluted with 5 mlO of saline and titrated to pll 7.0 with 100 mM~NaOH. Total acid output is computed from the product of acid concentration and Yolume of juice secreted. Compounds are administered intravenously tO.l ml-/kg-) via a cephalic vein or orally in a gelatin cap~e when a secretory plateau (3 consecutive readings within 10%~ has ~ attained. Secretion is mea~u~d for a period of 3 hours ~oll ~ ng administration of test ~ound The results obtained in the atrium and ar.ino-pyrine tests are predictive of ~cti~ity in the rat and dog tests.
No overt tox~city or slde ef fects were noted dur~ng the rat or dog tests. The compound 5-[4-~2-allylguanidino)-1,2,3-triazol-2-yl]~aleramide was administered intravenously to groups of two anaesthetised ~ats and four conscious mice at doses which were respectively ten times and one hundred times the dose, in mg/kg., which produced an approximate 50% inhibition ~f gastric secretion in the anaesthetised rat. No toxic symptoms were noted in any of the dosed animals, ~u~ ~7 The N-methylcyanoguanidine group in known H-2 receptor antagonists is potentlally changeable into the mutagenic N-Nitroso N-methylcyanoguanidlne group in the mamma]ian body (Pool et al., Toxlcology, 1979, 15, 69). The corresponding group ln the compounds of the present inventlon, CoNR2R3, is not potentially changeable into carcinogenic nitroso derivatives when R2 and R3 are hydrogen atoms.
According to a ~urther feature of the invention, lO there is provided a pharmaceutical composition which comprises a guanidine derivative of the invention ln association with a non-toxic pharmaceutically-acceptable diluent or carrier.
The pharmaceutical composition may, for example, be 15 in a form suitable for oral, rectal, parenteral or topical admlnistration, for which purposes it may be formulated by means known to the art into the form oE, for example, tablets, capsules, aqueous or olly solutlons or suspension, emulsions, dlspersible powders, suppositories, sterile 20 injectable aqueous or oily solutlons or suspenslons, gels, creams, ointments or lotions.
In addition to the guanidine derivative of the formula I, the pharmaceutical composition of the invention for oral, rectal or parenteral administration may also 25 contain, or be co-administered with, one or more known drugs selected from antacids, for example aluminium hydroxide -magnesium hydroxide mixtures; antipepsin compounds, for example petstatin; other histamine H-2 antagonists, for example cimetidine or ranitidine; ulcer healing agents, for 30 example carbenoxolone or bismuth salts, anti-inflammatory agents, For example 35 ~~~~~~~ -- -1~2(~4'77 ibuprofen, indQmethacin, naproxen or aspirin prostaglandins, for exa~nple 16,16 dimethylprostaglandin E2; classical antihistamines (histamine H-l antagonists), for example repyramine or diphenhydramine; antichol- ¦
inergic agents, for example atropine or propantheline bromide; ar~iolytic agents, for example diazepam, chlordiazepoxide or phenobarbital.
The pharmaceutical composition of the invention for topical administration may also contain, in addition to the guanidine derivative, one or more class-ical anti-histamines (histamine H-l antagonists~, for exa~ple mepyramine or diphenhydramine and/or one or more steroidal anti-inflammatory agents, for example fluocinolone or triamcinolone.
A topical formulation may contain 1-10% wJw of the guanidine derivative of the invention. A
preferred pharmaceutical composition of the invention is one suitable for oral administration in unit dosage form, for example a tablet or capsule which contains between 5 mg. and 500 mg. of the guanidine derivative, or one suitable for intravenous, subcutaneous or intra-muscular injection, for example a ~terile injectable containing between 0.1% and 10% w/w of the guani~ine derivative.
The phannaceutical cQmposition of the in~ention will normally be administered to man for the treatment vf peptic ulcers and other conditions caused or exacerbated by gastric acidity in the same general l~lanner as that employed for cLmetidine, due allowance -- 30 -i?eing madP in terms of dose levels for the potency and 3uration of acticn o~ the gEnid~ne derivative of the pre~ent lnvention relati~e to cimetid~ne, Thus each patient will receive an oral dose of between 15mg. and 1500 mg.,and preferably between 20 mg. and 200 mg., of guanidine deri~ati~e or an intravenous, subcutaneous or intra-muscular dose of between l,S mg, and 50 mg.~ and preferably between 5 ~ng. and ~0 mg.~ of the guanidine . - ~3 derivative, the cDmposition being administered 1 ~o 4 times per day. The re~tal dose wi~1 be approxLmately the same as the oral dose. The - composition may be administered less frequently wh~n it contains an amount of guanidine derivat:i~e which is a multiple of the al.tount which is effective when given 1-4 tL~.es per day.
The invention is illustrated, but not lLmited, by the following Examples. The n.m.r. spectra are quoted in ~ relatiYe to tetramethylsilane ( ~ = O) as internal standard (s = singlet, d = doublet, t = triplet; q =
quartet, m - multipletl br = broad). The temperatures are in degrees Centigrade~ The following contractions are used:~
~OAc - acetic acid D~ = d~methyl forma~ide ether - diethyl ether DMSO = dLmethylsulphQxiae MeOH - methanol EtOH = ethanol T~F = tetrahydrofuran EtOAc = ethyl acetate ~ ttention is drawn to the fact that 3-nitro-pyrazole (~xample lO) and 4-nitrotriazole (Example 8) 25 are both explo510n hazards.

~ , _ ~

~Z~77 31723 - 2~ -Example 1 .

A mixture of 4-t4-12~propylguanidino]pyrimid-2-ylthiolbutyronitrile (0.18 g.) and concentrated sulphuric acid (1.5 ml.) was stirred at ambient t~mp-erature for 2,5 hours. The reaction mixture was cooledin an ice-~ath and basified by careful drop~ise addition of concentrated aqueous ammonia ~s.~. 0.880). The resulting whit~ precipitate was collected, washPd with water and allowed to dry. The solid was purified`by 10 preparati~e t.l.c. using Merck silica 60F254 and CHC13/
MeOH/aqueous ammonia (s.g. 0.880~ 8:2:0,3 ~/v/v as eluant.
The purified product was converted in EtO~ solution to the ~aleate salt to gi~e 4-(4-~2 - propyl_guanidinoi-pyrimid - 2-ylthio)butyramide maleate (0.10 g.~ m.p.
15 200-202.
The starting material may be obtained as follows:-4~Chloro~utyronitrile (0.23 g.~ in EtO~.(2 ml.) was added to a solution of 2-thiocytosine (0.25 g.) in 0.5N aqueous ~aOH (5 ml.) and the mixture stirred for 18 hours. A further portion of 4-chlorobutyronitrile ~0.23 g.~ was added and the mixture stirred a further 24 hours. The solution was concentrated in vacuo to 2 ml.
and cooled and the crystalline precipitate collected to 25 give 4-[4-aminopyrimid - 2-ylthio]butyronitrile (0.3 g.) m.p. 93-100.
A mixture of 4-14-aminop~rLmid-2-ylthio~-butyronitrile (0.75 g.), n-propylisothiocyanate 10.8 g.) and pyridine (5 ml.) was heated at 130 for 2 hours and then heated under reflux for 18 hours. The solvent was removed by evaporation in vacuo and the residual oil was purified by medium pressure chromatography on silica using CHC13/MeOH 9.~5;0.25 v~ as eluant. A
portion of the purified product (0.3 g.) and EtOH
(5 ml.) was added to EtO~ saturated with ammonia (10 ml.) and mercuric oxide (0.22 g.). After 15 minutes the ~ 7~ 31723 reaction mlxture was filtered through diatomaceous earth and the filtrate was eYaporated to give a white semi-crystalline solid which was purified by~medium pressure chrQmato~raphy on silica using CHC13~MeO~I/
aqueous ~,unonia (s.g. 0.880~ 9:1:0.1 ~/v/~ as eluant.
There was thus obtained 4-(4-[2-propylguanidino]~yrimid-2-ylthio]butyronitrile (0.18 g,) which was used without further purification.
~xample 2 A mixture of 5-~4-[2~propylguanidino]pyrimid~
2-yl~valeronitrile (0.25 g.) and concentrated sulphuric acid (2 ml.~ was stirred at ambient temperature for 3.5 hours. The reaction mixture was cooled in an ice bath and basified by careful dropwise addition of lS concentrated aqueous ~monia (s.g. 0.880). The resulting white precipitate was collected, washed with water and allowed to dry. The 501 id was purified by medium pressure chromatography on silica gel using CHC13/MeOH/aqueous ammonia (s.g. 0.880) 8:2:0.3 v/v/Y as eluant to give 5-(4-[2-propylguanidino]pyrimid-2-yl~valeramide , (0.15 g.~, m.p. 212-214.
The starting material may be prepared as follows:-~ mixture of ethyl S~cyanoYaler~midate (21 g.) and ammonium chloride (7.5 g.) in MeO~ ~100 ~1.
was stirred overnight at room temperature and then evaporated to dryness. The residue was heated under reflux in EtOH (150 ml.) with triethylamine (56 g.) and 2-chloroacrylonitrile ~36 g,). After 2 hours the mixture was evaporated to dryness and the residue was then stirred in water (300 ml.) containin~ sufficient HOAc to gi~e a pH of 4. Charcoal was added and after 30 minutes the mixture was filtered and the aqueous solution extracted with EtOAc (2 x 150 ml.). The aqueous layer was basified with aqueous sodi~ hydroxide to p~ 10 and extracted with EtOAc (3 x 150 ml.). The combined e~tracts were evaporated to dxyness and the residue recrystallised from acetonitrile to giYe 2-(4 cyanobutyl)~4-aminopyrlmidine.
A mlxture of 2~4-cyanobutyll~4~ninopyrLmidine ~1.0 g.), n-propylisothiocyanate ~0.57 g.) and pyridine (25 ml.) was heated under reflux for 3 hours. The solvent was remoYed by evaporation in acuo and the residue was purified by medium pressure chr~natography on silica gel using CHC13~MeOH 9.75:0.25 v~Y as eluant.
The purified product (0;85 g.~ in EtOH Clo ml.2 was added to EtO~ saturated with ~nonia (30 ~nl.) and mercuric oxide (0.6 g.~. After 15 minutes the reaction ~ixture was filtered through diatomaceous earth and the filtrate was e~aporated to give 5-~4-~2~propylguanidino~pyrimid 2-yl)-~aleronitrile tO.85 g.~ which was used without furtherpurification.
Exam~les 3-5 The process of Example 1 was repeated using the appropriate starting materials to giYe the following con-~pounds:-~ /C~ ~ ~ ~ S~c~ ~ 3- C~ æ

E~nple R Salt ~ P Yield _.
_ 3 CH3 maleate 207-208 48 4 i-C3H7 maleate 178-179 40 - c2~5 _ 180~182 32 The starting material may be prepared by repeating the third part of Example 1 using the appropriate isothiocyanate in place of n-propylisot.hio-~ 77 31723 cyanate.
Exa ple 6 A solution of 4-~2-~3~ethylthioureido)pyrid-6-ylthio~utyramide (0.25 g.) in methanolic ammonia was S treated with yellow mercuric oxide (O.S g.~ and the mlxture stirred at room temperature for three hours, The ~ixture was filtered and the filtrate evaporated to dryness. A solution of the residue in acetone was added to a solution of maleic acid in acetone and the crystalline precipitate collected to ~iYe 4~2-~2-ethylguanidino~pyrid-6-ylthio]butyramide hydrogen maleate (0.22 g.), ~.p. 174-176.
The startiny ~aterial may be prepared as follows:-A mixture of sodium (1.84 ~ EtOH (100 ml.
and 4-I~ercaptobutyric acid (5.2~ g.) was heated to reflux and then treated with 2,6-dibromopyridine (9.5 g.), and the mixture heated under reflux for 18 hours and then evaporated to dryness. The residue was partitioned between water and ether and the aqueous phase was acid-ified with HOAc and extracted with ether. The ether extract was dried and evaporated to dryness to giYe 4-(2-bromopyrid-6-ylthio)butyric acid ~g.5 g.), m.p.
72-74.
A mixture of 4-(2-bromopyrid-6-ylthio~butyric acid (7 g.) and thionyl chloride (35 ml~) was heated under reflux for 1 hour and then evaporated to dryness.
The residue was treated with concentrated aqueous ammonia ~70 ml.) and the mixture stirred vigorously for '~ ~.ours. The insoluble solid was collected to gi~e 4 (2-bromopyrid-6-ylthio)butyramide~ m.p. 87-8B.
A mixture of 4-(2-bromopyrid-6-ylthio)butyramide (5 g.) and concentrated aqueous ammonia ~25 ml.) w~s heated in a sealed tube at 180 for 24 hours. The mixture was cooled and diluted with water, and then extracted twice with EtOAc. The combined extracts were extracted ~ 77 31723 twice with ~i aqueous HCl and the aqUeOU!, acid extracts were com~ined, basified with 10 N aqueol~s NaO~l, and extracted with EtOAc. The EtOAc extract was ~ried and ~ evaporated to dryness to give 4-(2-aminopyrid~6~ylthio1-butyramide.
A mixture of 4-(2-aminopyrid-6-ylthio)butyr-a~nide ~0.25 g.), ethylisothiocyanate ~0.2 g.~ and acetonitrile (5 ml.) was heated under reflux for 18 hours and then cooled~ and the solid which crystallised was collected to give 4-[2-(3-ethylthioureido~pyrid-6-ylthio~butyramide 10025 g ~ which was used without further purification.
Example 7 The process of Exc~mple 6 was repeated using the appropriate starting material to giYe 4-E2-~2-propylguanidino)pyrid-6-ylthioJbutyramide hydrogen maleate (yield 15%)~ m.p. 138 140~
The starting material may be obtained by repeating the last part of Example 6~ using n-propyl~
isothiocyanate in place of ethylisothiocyanate~
Example_ A stirred mixture of unpurified 5-(4-~3-allyl-thioureidoi-1,2,3-triazol-2-yl~valeramide (0.09 g.)~
yellow mercuric oxide (0.13 g. ) and ammoniacal EtOH
(6M; 10 ml.) was kept at room temperature for 3 hours.
The mixture was filtered~ evaporated, and the residue r~issolved in a small ~olume of EtOAc/MeOH. This solution was treated with a solution~of maleic acid ~.037 g.) in a small volume of acetone and then diluted ~ith ether to ~ive 0.07 g. of 5- t4-[2-allylguanidino]
1,2,3-triazol-2-yl)valeramide maleate, m.p. 116-118.
The startin~ material may be obtained as f~llows:-A stirred solution of 4-nitro-1~2,3-triaæole (23.0 g.l in dry ~MF (135 ml.~ was treated at room t~nperature with a dispersion of sodium hydride ~4.8 g.) ~ 31723 in mineral oil (4.8 g.). The mixture was stirred for 30 minutes and then treated with 5~brQmc)Yaleronitrile (33.0 g.2. The mixture was stirred overnight at roo~
temperature and then poured into water. The product was extracted into EtOAc and purified by column chromat-ography on silica gel (1 kg.) eluted with EtOAc/petroleum ether (b.p. 60-80) 1:1 ~/v to give 22.3 g. of 5 nitro-1,2,3~triazol-2-yl)valeronitrile as an oil.
A mixture of 5-(4-nitro^1,2~3-triazol-2-yl)-~aleronitrile t2.~ g.) and concentrated sulphuric acid (2 ml.~ was kept at room temperature or 5 hou~s. The mixture was poured into ice-water and basified with aqu~ous NaOH~ The mixture was saturated with NaCl and extracted with EtOAc. The extract was dried (MgS04) and evaporated to give 1.65 g. of unpurified 5-(4-nitro-1,2,3-triazol-2-yl)valeramide.
A stirred mixture of unpurified 5-(4-nitro-1,2,3-triazol-2-yll~aleramide (1.65 g.~ palladium on charcoal (5~ wJw; 0~8 g.), and HOAc was kept at room temperature under one atmosphere of hydrogen until 610 ml.
of hydrogen had been absorbed. The mixture was filtered and evaporated. The residue was triturated with hot isopropanol and filtered to giYe 0.4 g of 5~~4-amino-1,2,3-triazol-2-yl)~aleramicle~ m.p. 147~148.
A mixture of 5-(4-amino-1,2~3-triazol-2--yl~-valeramide (0.18 g~)~ allylisothiocyanate ~0.11 g.), and DMF ~5 ml.~ was stirred at room temperature o~ernight.
The mixture was poured into water and extracted with EtOAc. The extract was dried (MgS04l and evaporated to give 0.09 g. of 5-(4-[3-allylthioureido~-1,2,3-triazol-2-yl)~aleramide which was used without further purification.
Example A mixture of 5-(4~12 allylguanidino~-1,2~3~
triazol-2-yl~aleramide maleate (0.11 g.), PtO~ (0.08 g.), EtOH ~5 ml.~ and DMF ~1 ml,) was stirred at room temp-erature under one atmosphere of hydrogen until 50 ml. of hydrogen had been absorbed. The mixture was filterecl and - 3~ -evaporateu to gi~e an oil that was partitione~ between EtOAc and a~ueous Na~C03. The oryanic phase was dried (MyS04~ and evaporated to give a portion of the product.
- The aqueous phase was saturated with l~aCl, evaporated to dryness, stirred overnight with acetonitrile, and filtered to give a solution of a second portion of the product. Tne two portions of product were combined, the solvent evaporated, and the residue redissolved in a sl,all volume of MeO~tOAcO This solution was-treated with a solution of maleic acid (0.03 g.~ in a small volume of acetone and then diluted with ether to precipitate an oil, which slowly solidified. The solidified oil was filtered and washed with ether to give 0.07 g. of 5-(4-~2-propylguanidinoj 1,2,3-triazol-2-yl)valeramide maleate hemihydrate, ~.p. 67-69.
Example 10 A ~Qixture of 5-(3-12-propylguanidino]pyrazol-l-yl)valeronitrile (1.1 g.) and concentrated sulpnuric acid ~3 ml.l was stirred for 18 hours at room temperature.
The solution was added to ice-water and basified with lON aqueous NaOH. Extraction with EtOAc and work up gave a brown impure oil which was converted in acetone to the maleate salt. Crystallisation was induced by addition of a sMall volume of ether to give 5-(3-~2-propylguanidinoJpyrazol~l-yl~Yaleramide hydrogen maleate (0.45 g.), m.p. 132-134 (yield 26~)o Tne starting material may be prepared as follows:~
Sodiu~ hydride paste (6.16 g. of 61~ w/w suspension in liquid paraffin) was added portionwise over 30 minutes to a solution of 3-nitropyrazole (17.4 g.) in dry DMF (150 ml.) with external ice cooling to maintain the temperature at 20~30. The mixture was stirred for 45 minutes an~ to the almost clear solution was added 5~bromovaleronitrile (25 y.) over 30 minutes, at 25-30, and the mixture was stirred for 4 hours.

~ 7~ 31723 ~ater (450 ml~ and EtOAc (450 ml.~were adde~ and the upper layer was separated, dried (l~igS04J and evaporated ln ~acuo to an oil which was a mixture of 5~ nitro-- pyrazol~l-yl)Yaleronitrile and 5-(5-nitropyrazol-1-yl)-valeronitrile. The oil was ~ivi~ed into t~lO 15 g.
portions which were fractionated on a silica coluMn (3.5 CIil diameter x 100 cm long) eluted at 2 atmospheres by EtOAc~60-80 petroleum ether (3:7 v~v]. The 1,5 isoliler was eluted first followed by the 1,3 isomer. The 5-(3-nitropyrazol-1-yl1valeronitrile had m.p. 32-33.
To a solution o~ 5-(3-nitropyrazol-1-yl) valeronitrile (9.16 g~ in dry T~ (200 ml.~ was added 5% w~w palladium on carbon (1.8 g.). The mLxture was st rred at 20 under an atn~osphere OL hy~rogen.
3.2 Litres of hydrogen were a~sorbed oYer 4 hours. The catalyst was filtered off and the filtrate was evaporated in vacuo to give 5-(3-aminopyrazol~l-yl)valeronitrile as an oil.
h solutivn of 5-S3-aminopyrazol-1-yl)valero-2~ nitrile (1.0 g.) in acetonitrile (10 ml.) was treated~-ith n-propylisothioc~anate ~0.74 g.) and the solution h~ated un~er reflux on the steam bath for 6 hours, ~vaporation of the solvent gave a brown gum which on trituration with ether/EtOH gave 5-(3-13-propylthioureido]-pyrazol-l-yl)valeronitrile as a white solid ~1.01 g.).
A solution of 5-(3-13-propylthioureido]-pyrazol-l-yl)valeronitrile ~1.01 g.3 in saturated methanolic - amnlonia (30 ml.) was treated with oranse mercuric oxide (0.82 g.) and the suspension stirred at room temperature for 18 nours. The black suspension was filtered through diatomaceous earth and the filtrate evaporated to gi~e 5-(3-[2-propylguanidino]pyrazol-1-yl)valeronitrile as a brown oil which was used without further puriication.
Examples 11-12 The process of Example 10 was repeated using the appropriate startin~ materials to yive 5-~3-(2~

~ 7~ 317~3 methylguanidino2pyrazol~1-yl~yaleramide 1.25 maleate ~yield 14~ ~n.m.r~ in d6DMSO; 1.8 ~m, 4H~; 2.3 (t, 21i); 3.1 (s, 3hl; 4.3 (t, 2H~I 6.2 (d, lH~; 6~3 (s, 2.5H); 7.95 ~d, lH)~ an~ 5-[3-(2~ethylguanidino)pyra~ol-l--yl~valeramide maleate, m.p. 132-134 (yield 23~).
The starting n.aterials ma~ be ~repared by repeating the fourth and fifth parts of Ex~nple 10 using ~nethylisothiocyanate and ethylisothiocyanate respectively in place of n-propylisothiocyanate.
Example 13 A solution of methyl 3-[2~(2-methylguanidino)-thiazol ~-yl]benzoate hydrochloride (1 g.) in ethanolic methylamine (30% w/v) was allowed to stan~ at room tem~erature for 4 days and then evaporatea to dryness.
The residue was recrystallised frQm i~eO~ to give 0.27 g.
of N-methyl-3-12 (2-methylguanidino)thiazol-4-yl~-benzamide, m.p. 111-113 (yield 30~)0 Tne starting material may be prepared as follo~s;~
A solution of 3-cyanophenacylchloride (3.6 g.3, in ~tOH ~30 ml.) was added to methylamidinothiourea ~2.65 g.) in EtOH (30 ml.) and the mixture was heated under reflux for 1 hour. Tile crystalline proauct was filtered off and washed with EtOI1. A solution of this material (3.5 g.) in a l~ixture of concentrated aqueous hydrochloric acid (40 1~1.) and HOAc (40 ml.) was heated under reflux for 16 hours. The mixture was e~aporated to dryness and the residue in MeO~ (100 ml.) treated with thionyl chloride ~15 ml.). The mixture was stirred for 2 hours and then evaporated to dryness. The residue was triturated with acetonitrile to give methyl 3-[2-(2-methylguanidino)thiazol-4-yl~benzoate hydro-chloride, having the following n.m.r. in ~6DMSO:-3.1 (d, 3H); 4.0 (s, 3H); 6.7 (s, 2H); 7.6 (s, 2H);
35 7.8-8.6 (m, SH).

Example 14.
The process of Ex~mple 13 was repeated using 1,2-ethylene diamine in place of ~ethylamine to give - N-(2-aminoethyl)-3-~2~(2-methylguanidino)thiazol-4-yljbenzamide m.p4 214-216 ~yield 32%~.
~xam~le 15 To methyl 3-[2-guanidinothiazol-4-ylmethylthio]-propionate ~0.775 g.), in MeOH ~10 ml.~ ~as added hydrazine hydrate (2 ml.; 64% w/v~ and the solution 10 stirred at room temperature for 18 hours. The resulting suspension was filtered and the filtrate crystallised from MeOH to giYe 3-~2~guanidinothiazol-4-ylmethylthio~-propionylhyarazide as a white solid (0 23 g ~ ~.p.
185-187.
The starting material ~ay be prepared as follows:-To 2-guanidino-4-chlorQmethylthia2ole hydro-chloride (3.86 g.) and methyl 3-mercaptopropionate ~3.0 g.) in EtOH (45 ml.) at O was added sodium hy~roxide (1.6 g.) in water (15 ml.) o~er 15 minutes. The reaction mixture was allowed to attain roQm temperature and to stand or 18 hours. The solution was poured into water and extracted with EtOAc. The extract was washed with aqueous sodium hydroxide solution, water~ dried and evaporated to gi~e methyl 3-(2-guanidinothiazol-4-yl~
methylthio)propionate as a yellow oil which was used without further purification.
Example 16 Methyl 3~(2-guanidinothiazol-4-yl)cyclopentane 30 carhoxylate ~o . 40 g ~ ? and a solution of methylamine in EtOH (33% w~v, 15 ml.l was allowed t.o stand at ambient temperature for 60 hours. The solvent was re~oved by evaporation in Yacuo and the residue was purified by me~ium pressure chr~matography on silica ~el using 35 CHC13JMeOHJaqueous a~rGOnia ~s.g. 0.88~ 8;2;0.3 vJy/v as eluant to giYe N~methyl~3-(2~guanidinothiazol-4-yl)-cyclopentane carboxamide (0.27 g ~, m.p. 216-218.

7~
~ 34 -The starting material may be prepared as follows:~
A mLXtUre of 3-methoxycarbonyl~l-ch~oroacetyl-~ cyclopentane (1.02 g.~ and amidinothiourea (0.6 g.) in MeO~ (10 ml.) was heated under reflux for 1 hour. Thesolvent ~as removed by e~aporation in vacuo and the residue was purified by low pressure chra~atography on silica gel using C~C13/MeOh~aqueous an~onia (s.g. 0.880) 9:1~5:0~1 v~Yfv as eluant. The product was ~riturated with ether to give methyl 3-(2-guanidinothiazol~4-yl)-cyclope~tane carboxylate (1.14 g,~, m.p. 124-126.
ExamE~e 17 A solution of 3-~-guanidinothiazol-4~yl]-benzonitrile (0.5 g~ in a ~ixture of HOAc (10 ~1.) and concentrated aqueous hydrochloric acid (20 ml.) was heated at 90 for 6 hours. The mixture was then eYap-orated to dryness and the residue dissolYed in MeOH
(15 ml.l and thionyl chloride ~3 ml.~ added dropwise.
After stirring at ambient temperature for 2 hours the 2~ mixture was heated under reflux and then allowed to cool.
The crystalline ester was filtered off and stirred in a solution of methylamine in EtO~ (30% w/~; 25 ml~ for 4 days at ambient temperature. The mixture was evaporated to dryness and the residue purified by l~dium pressure liquid chromatography on silica gel using chloroform~
MeOH/aqueous ammonia (s.g. 0.8802 9:1;0.05 v/~Y as ~ nt ~to giYe 0.04 g. of N-methyl-3~12~quanidinothiazol-4-yl}benzamlde m.p. 232-235~yield 7~).
The starting material may be prepared as follows:~
A mixture of 3-cyanophenacyl chloride (1.78 g.) and ~midinothiourea (1.2 g.l in ~tOH (40 ml.) was heated under xeflux for 1 hour. The solid precipitate was filtered off, dissolved in hot water (100 ml.) and the solution bacifled with sodium bicarbonate. The precipitated solid was filtered off and dried to gi~e 3-~2-guanidlnothiazol-4-yl]benzonitrile which was used without further purification.

J 1 / ' _ Exam~le 18 ..
A solution of 4-[2~(2~t~butylguanidino)pyrid- j 6-ylthioJbutyronitrile hydrogen maleate (0,1 y.~ in - concentrated sulphuric acid (0.5 ml.) was kept at room temperature for 72 hours. The solution WclS added to crushed ice and then basified with 10l~ aqueous NaOI. and the mLXtUre extracted three times with EtOAc. ~he combined extracts were dried and evaporated to dryn~ss.
A solution of the residue in acetone was added to a solution of maleic acid in acetone, and the crystalline precipitate was collected to give 4-(2-guanidinopyrid-6-ylthio)butyramide hydrogen maleate (0.04 g.~, m.p. 169 170.
The starting material may be prepared as lS follows:~
2-Amino-6-bromopyridine (40 g,) was added to a snlution of benzyl mercaptan (83.7 ml~ and sodium Cl~ . ~ g. ) in EtO~i and the mixture stirred and heated un '7- reflux for 72 hours. The mixture was evaporated to dryness and the residue stirred with a mixture of wat~r (1.4 1.~ and EtOAc ~700 ml,~ and acidified to' pH 1 with concentrated aqueous hydrochloric acid. The precipitated solid was collected to gi~e 2-amino-6-benzylthiopyridine hydrochloride (30 g.), m.p. 189-191.
A solution of 2-amino-6-benzylthiopyridine hydrochloride (47.2 g.~ in liquid NH3 (700 ml.3 was fitirr~,d while Na (17.0 ~,2 was added in small portions.
~hen the addition was complete NH4Cl (21.9 g.) was added and then the mixture was eYaporated to dryness. The residue was dissolYed in a mixture o~ EtOH (100 ml.) and H20 (100 ml.) and the mixture treated with 4-bromo-butyronitrile (23 ml.) and stirred at room temperature for 18 hours. The solution was evaporated to dryness and the residue was partitioned between ~M aqueous HCl and ether. The aqueous phase was basified with lON
aqueous NaOH and extracted with EtOAc. The extract was dried over Na2S04 and evaporated to dryness to gi~e I

~2~ 77 4-(2-amino~yrid-6-ylthio)butyronitrile (36.1 y.) which was used without further purification.
A solution of 4-(2-aminopyrid-6-ylthio)~
butyronitrile ~0.39 g.1 and t-~utylisothiocyanate (0.25 g.) in T~ (10 ml.~ was stirred under an aryon atmosphere while adding a solution of n--~utyl lithium in hexane (1.55M; 2 ml.). The mixture was stirred at room temperature for three hours and hen evaporated to dryness. The residue was partitioned between EtOAc and water and the EtOAc phase was dried and evaporated to dryness. The residue was recrystallised fr~m EtOH to giYe 4-[2-(3-t-butylthioureido)pyrid-6-ylthiolbutyro~
nitrile (0.32 g.), m.p, 156-157.
A solution of 4-[2-~3-t-butylthioureido)-pyrid-6-ylthio]butyronitrile (0.25 g.~ in methanolic ammonia was treated with yellow mercuric oxide (0.3 g.) and the mixture was stirred at roQm temperature for four hours and then filtered. The filtrate was evaporated to dryness and the residue partitioned between N aqueous hydrochloric acid and ether. The aqueous phase w~s basified with lON aqueous NaOH and extracted with EtOAc and the extract was dried and then eYaporated to dryness.
A solution of the residue in acetone was added ~o a solution of ~aleic acid in acetone, and the solution was diluted with ether. The crystalline precipitate was collected to gi~e 4-[2~(2-t-butylguanidino)pyrid-6-ylthio~
~utyronitrile hydrogen maleate (0.22 g,), m.p. 146-147.

_ /
~ . .. .

7~

_ 37 _ Example 19 A tablet containing 100 mg. o~ 4-(4 [2-propyl-guanidinolpyrimi~2-yl~hio)bu~yramlde may be prep~red using ingredients ln the following proportions:-(a) Tablet Core. mg./ta~let Active agent 200 Lactose 68.5 Calci~Lm carbQxymethylcellulose 22.S
Polyvinylpyrrolidone ~.o Magnesium stearate 3.o (b~ Tablet Coat mg.~tablet Hydroxypropylmethylcellulose 4.5 Polyethylene glycol o.g Titanium dioxide 1.35 lS The active agent, lactose and calcium carboxy-methylcellulose are mixed. An aqueous solution of poly-vinylpyrrolidone is added, and the mass is then mixed - until it is suitable for granulation. The mass is then gr~nulated and dried. The magnesium stearate is blended with the dried granules and the resulting mixture is compressed into tablets. The tablets are film-coated using an aqueous or solvent suspension of hydrQxypropyl-methylcellulose, polyethylene glycol and titanium dioxide~

Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the manufacture of a compound of the formula III:- III
and the activated derivatives thereof, including the alkyl ester of the formula IIIA:- IIIA
or of the formula IV:- IV
in which R1 is a hydrogen atom or a 1-10C alkyl, 3-8C
cycloalkyl, 4-14C cycloalkylalkyl, 3-6C alkenyl, 3-6C
alkynyl, 1-6C alkanoyl, 6-10C aryl, 7-11C aralkyl or 7-11C aroyl radical, the aryl, aralkyl and aroyl radicals being optionally substituted on the aryl ring by one or two substituents selected from halogen atoms and 1-6C alkyl, 1-6C alkoxy, 1-6C alkylthio, trifluo-romethyl, hydroxy and amino radicals; in ring X the dotted line is a double bond on one side of the nitrogen atom and Z is a carbon or nitrogen atom such that ring X is a 5- or 6- membered aromatic hetero-cyclic ring which contains at least one nitrogen atom and may optionally contain one or two additional hetero atoms selected from oxygen, nitrogen and sulphur atoms, which heterocyclic ring may, where possible, carry one or two optional substituents, the optional substituents on ring X being selected from fluorine, chlorine and bromine atoms and 1-6C alkyl, 1-6C alkoxy, trifluoromethyl, hydroxy and amino radicals; Ra is 1-6 C alkyl, A is a phenylene or 5-7C
cycloalkylene radical or a 1-8C alkylene chain which is optionally substituted by one or two 1-3C alkyl radicals and into which is optionally inserted, as part of the backbone of the chain, one or two groups selected from oxygen and sulphur atoms and NH, 1-6C
N-alkyl, cis and trans vinylene, ethynylene, phenyl-ene and 5-7C cycloalkylene radicals, provided that the shortest link between ring X and C=D is of at least 3 atoms, provided that when an optional insertion is made in chain A which results in the inserted group being directly attached to C=D the inserted group is other than an oxygen or sulphur atom or an NH or N-alkyl radical, and provided that no two insertions selected from oxygen and sulphur atoms and NH and N-alkyl radicals are directly attached one to the other; and D is an oxygen or sulphur atom; which comprises:

(a) when ring X is a thiazole ring and A
contains no inserted group or the inserted group is phenylene, reaction of a compound of the formula XII:- XII

with a compound of the formula XIIIA, XIIIB; or XIIIC, respectively:
XIIIA
XIIIB
XIIIC

in which R1 and Ra are defined as above; Hal is a chlorine or bromine atom and R5 is a hydrogen atom or the optional substituent on the thiazole ring;
(b) constructing the left hand chain on the ring X from a corresponding compound having an amino group on ring X by reacting the said amino group with an isocyanate of the formula R1-N=C=S and subsequently reacting the resulting thiourea with ammonia in the presence of mercuric oxide, and constructing the ring X bearing an amino group and the right hand chain on ring X by;
(i) reducing a nitro group on ring X to the corresponding amino group on ring X by a conventional method;
(ii) when ring X is a pyrimidine, by reacting a substituted amidine of the formula XIVA, XIVB or XIVC, respectively:
XIVA

XIVB
XIVC
with 2-chloroacrylonitrile;
(iii) when group A is a 1-8 alkylene chain into which is inserted a vinylene or ethyn-ylene radical, introducing group A by reaction of a compound of formula XV:- XV
with a compound of the formula XVIA, XVIB or XVIC, respectively:
XVIA
XVIB

Q-A'-CN XVIC
in which the groups M and Q when reacted together provide a vinylene radical or an ethynylene radical by a conventional method and A3 and A4 are fragments of A, including direct bonds, and are such that A3-vinylene-A4 or A3-ethynylene-A4 falls within the definition of A given above.
(iv) when group A is a 1-8C alkylene chain into which is inserted an oxygen or a sulphur atom or an NH or N-alkyl radical, reaction of a compound of the formula VIA:
VIA
with a compound of the formula VIIIA, VIIIB
or VIIIC, respectively:
VIIIA
VIIIB

or reaction of the compound of the formula VIIA:
VIIA
with a compound of the formula IXA, IXB or IXC, respectively:
IXA
IXB

in which G is an oxygen or sulphur atom or an NH or N-alkyl radical, R4 is a displaceable radical and A1 and A2 are fragments of A, including direct bonds and are such that A1-G-A2 falls within the definition of A
given above;

(c) when group A is oxygen or sulphur or an NH or N-alkyl radical, reaction of a compound of the formula VI:- VI
with a compound of the formula VIIIA, VIIIB or VIIIC, respectively, or reaction of a compound of the formula VII:
VII
with a compound of the formula IXA, IXB or IXC, respectively:
(d) when D in III is oxygen, hydrolysis of the corresponding compound of the formula IIIA or IV;
(e) when IIIA is required, esterification of the corresponding compound of the formula III.

2. Compounds of the formula III:

III
and the activated derivatives thereof, including the alkyl ester of the formula IIIA:
IIIA
or of the formula IV:- IV
in which R1 is a hydrogen atom or a 1-10C alkyl, 3-8C
cycloalkyl, 4-14C cycloalkylalkyl, 3-6C alkenyl, 3-6C
alkynyl, 1-6C alkanoyl, 6-10C aryl, 7-11C aralkyl or 7-11C aroyl radical, the aryl, aralkyl and aroyl radicals being optionally substituted on the aryl ring by one or two substituents selected from halogen atoms and 1-6C alkyl, 1-6C alkoxy, 1-6C alkylthio, trifluo-romethyl, hydroxy and amino radicals; in ring X the dotted line is a double bond on one side of the nitrogen atom and Z is a carbon or nitrogen atom such that ring X is a 5- or 6- membered aromatic hetero-cyclic ring which contains at least one nitrogen atom and may optionally contain one or two additional hetero atoms selected from oxygen, nitrogen and sulphur atoms, which heterocyclic ring may, where possible, carry one or two optional substituents, the optional substituents on ring X being selected from fluorine, chlorine and bromine atoms and 1-6C alkyl, 1-6C alkoxy, trifluoromethyl, hydroxy and amino radicals; Ra is 1-6 C alkyl; A is a phenylene or 5-7C
cycloalkylene radical or a 1-8C alkylene chain which is optionally substituted by one or two 1-3C alkyl radicals and into which is optionally inserted, as part of the backbone of the chain, one or two groups selected from oxygen and sulphur atoms and NH, 1-6C
N-alkyl, cis and trans vinylene, ethynylene, phenyl-ene and 5-7C cycloalkylene radicals, provided that the shortest link between ring X and C=D is of at least 3 atoms, provided that when an optional insertion is made in chain A which results in the inserted group being directly attached to C=D the inserted group is other than an oxygen or sulphur atom or an NH or N-alkyl radical, and provided that no two insertions selected from oxygen and sulphur atoms and NH and N-alkyl radicals are directly attached one to the other; and D is an oxygen or sulphur atom; whenever made by the process of Claim 1.