Patent GB-1445824-A (GB)
Title: Imidazo-4,5-b pyridines
IPC: A61P9/04
Filed: 1974-02-01
Abstract: 1445824 lmidazo[4,5-6]pyridines DR KARL THOMAE GmbH 1 Feb 1974 [3 Feb 1973 12 Dec 1973] 04808/74 Heading C2C The invention comprises compounds of formulµ and their N-oxides and acid addition salts, [wherein R 1 , R 2  and R 3 , which may be the same or different, each represents a hydrogen or halogen atom; a hydroxy, alkyl, allyloxy, benzyloxy, alkylthio, alkylsulphinyl or alkylsulphonyl group; an amino group optionally substituted by one or two alkyl groups; a morpholino or a piperazino group optionally substituted in the 4-position by a phenyl group or an alkyl group containing from 1 to 3 carbon atoms; or an alkoxy group containing from 1 to 4 carbon atoms, optionally substituted by a halogen atom or by a hydroxy, alkoxy, alkylthio, alkylsulphinyl, alkylsulphonyl, alkylamino, dialkylamino, piperidino, morpholino, thiomorpholino, thiomorpholino-S-oxide, thiomorpholino - S,S - dioxide, 4 - alkylpiperazino, 4 - phenylpiperazino, 4 - dimethoxyphenylpiperazino, 4 - phenylethylpiperazino, phenylethylamino, N - methyl - phenylethylamino or N - methyl - dimethoxyphenylethylamino group, provided that when two of R 1 , R 2 , R 3  are H, the other group is other than H, halogen, Me or NH 2 ; or two of the groups R 1  to R 3  together represent a methylenedioxy group and the remaining R 1 , R 2  or R 3  group is as hereinbefore defined; each of the above mentioned alkyl groups containing from 1 to 4 carbon atoms; R 4  represents a hydrogen atom; an alkyl group optionally substituted by a hydroxy, dialkylamino, phenyl dimethoxyphenyl, piperidino, morpholino, 4 - methylpiperazino or 4- phenylpiperazino group, each of the above mentioned alkyl groups containing from 1 to 4 carbon atoms, or a phenyl group optionally substituted by one or more halogen atoms or methoxy groups; provided that where R 4  represents a hydrogen atom at least one of the groups R 1  to R 3  is other than hydrogen; and R 5  represents a hydrogen atom, a halogen atom or an alkyl group of 1 to 3 carbon atoms. In examples, these compounds are prepared by reacting (1) a 2,3-diaminopyridine with (a) an appropriately substituted benzoic acid or an acid- or imido-chloride, ester, anhydride, amide (e.g. N-substituted) or thionomorpholide methiodide thereof, (b) an appropriately substituted 2- phenyl - 1,3 - dithiolan - 2 - ylium iodide, or (c) 4 - (1,3 - dithiolanylidene) - 3 - hydroxy cyclohexadienone; (2) a 3-amino-2-chloropyridine with an appropriately substituted benzamide; (3) converting Ia(R 4 =H) to I(R 4 #H) by reaction with an appropriate organic halide in presence of a base; or (4) interconversion of functional groups present by known methods. In method (1)(a), an intermediate salt or a 2- amino-3-benzamidopyridine or the corresponding amidine, and in method (2) a corresponding N<SP>1</SP>- (2 - chloro - 3 - pyridyl)benzamidine, may be isolated as intermediates. Also isolated are 2-(p-acetamidophenyl)-1H. imidazo[4,5-b]pyridine; and alkylthioalkoxy/ hydroxybenzaldehydes and their methyl ethers. Therapeutic compositions for oral, parenteral or rectal administration comprise compounds of the above formulµ, which are stated to have activity on the blood pressure and heart force, a positive inotropic effect, antiulcus activity, a platelet aggregation inhibiting effect and prolonging activity on the bleeding time.