| abstract |
Process for the preparation of 1H-benzimidazoles substituted in position 2, preferably those corresponding to the general formula in which R₁ represents a linear or branched alkyl containing 1 to 13 carbon atoms, a phenyl, halophenyl, 4-nitrophenyl, 4-methylphenyl, 4-cyanophenyl, 4-carboxyphenyl, benzyl, thienyl, furanyl, pyridinyl, 1,3- or 1 , 4-phenylene, R₂ represents a hydrogen or chlorine atom, nitro or carboxyl, 2- (4-chlorophenyl) -1H-benzimidazol-5-yl, or 2- (4-carboxyphenyl) -1H-benzimidazol-5-yl, and n is equal to 1 or 2.n n n According to the invention, an aldehyde is reacted together with a thionyl halide and a nitrogen aromatic heterocyclic compound, the product formed is then reacted with an optionally substituted 1,2-benzenediamine and the 1H-benzimidazole thus obtained is separated from the mixture. of reaction.n n n By this process, 1H-benzimidazoles are obtained in a single stage, under moderate conditions, with very high yields. |