GB945147A - Aza-benzimidazoles - Google Patents

Abstract

The invention comprises azabenzimidazoles of the general formula: <FORM:0945147/C2/1> and their physiologically tolerable acid addition salts wherein A represents a C1-3 alkylene radical R a dialkylamino (C1-3) group or a pyndidino, piperidino, piperazino or morpholino group, R1 represents a hydrogen atom, a hydroxyl or mercapto group, a C1-5 alkoxy group or a C1-5 alkylmercapto group and <FORM:0945147/C2/2> represents an unsubstituted or nitro substituted pyridine ring. The compounds may be prepared by subjecting an amino pyridine, containing a tertiary amino alkylamino group in a position ortho to the amino group or a substituent convertible into or replaceable by such a group, to ring closure with an alkanoic acid or a reactive functional derivative thereof such as an ester or imino ether thereof or with a carbonic or thiocarbonic acid derivative to form an azabenzimidazole ring and if necessary converting or replacing such a group. The alkanoic acid may be replaced by the alkane aldehyde or a functional derivative thereof and the product oxidised. The compounds may also be prepared by introducing into the 1-position of an azabenzimidazole directly or in stages of tertiary amino alkyl group substituents may be introduced into the imidazole nucleus of the products or one substituent replaced by or converted into another. The nitro group may be introduced into the pyridine ring. 2 - (b - Diethylaminoethylamino) - 3 - amino - 5 -nitro pyridine is prepared by condensing 2-chloro-3,5-dinitro pyridine with diethylaminoethylamine to give 2-(b -diethylaminoethylamino) -3,5-dinitro-pyridine and reducing the 3- nitro group. Similarly are prepared 2-(b -dimethylamino - ethylamino) -3-amino-5-nitropyridine and -3,5-dinitropyridine; 3-amino- and 3-nitro-4-(b -diethylaminoethylamino) - pyridines; 3-amino-and 3-nitro-4-(b -dimethylaminoethylamino) - pyridines, 3-amino- and 3-nitro-4-(b -morpholinoethylamino)-pyridines; 2-(b -diethylaminoethylamino) -3-amino- and -3-nitro-pyridines; 2-(b -dimethylaminoethylamino) -3-amino-and -3-nitro-pyridines; -4-(b -dimethylaminoethylamino) -3-amino -5-nitro- and -3,5-dinitro-pyridines. 5(6)-Nitro -7(4)-azabenzimidazole is prepared by ring closure with formic acid of 2,3-diamino-5-nitro pyridine in turn prepared by reacting 2-chloro-3,5-dinitropyridine with ammonia to give 2-amino -3,5-dinitro pyridine and reducing the 3-nitro group. Pharmaceutical compositions comprise azobenzimidazoles of the invention in admixture with or in conjunction with a pharmaceutical carrier suitable for enteral, parenteral or topical administration. Compositions may take the form of tablets, dragees, salves, creams, solutions, suspension or emulsions and may contain other therapeutically useful substances.