Abstract

4-Amino-5-(1H-benzimidazol-2-yl)-6-(4-chlorophenyl)pyridine-3-carbonitrile (3) was obtained from reaction of 2-cyanomethyl-1Hbenzimidazole 1 with chlorobenzaldehyde followed by reaction with malononitrile. Reaction of (3) with cyclohexanone, formic acid and
hydrazine hydrate afforded tetrahydrobenzonaphthyridine amine, pyrido[4,3-d]pyrimidin-4(3H)one and pyrazolo[4,3-c]pyridine-3-amine,
respectively. Heterocyclization of (3) with carbon disulfide and benzoyl isothiocyante gave the corresponding pyrido[3,4-
d]pyrimidindithione and thioxopyrido[4,3-d]pyrimidine methanone. While, the reaction of (3) with ethyl cyanoacetate, diethyl malonate
and nitrous acid afforded oxo-1,6-naphthyridin-3-carbonitrile, carboxylate and pyrido[4,3-d][1,2,3]triazine, respectively. Dihydroimidazol
pyridin-4-amine was obtained from reaction of (3) with ethylendiamine and carbon disulfide. Finally, cyclization of (3) with triethyl
orthoformate, in the presence of hydrazine hydrate, afforded pyrido[4,3-d]pyrimidin-3-ylamine.

Key words: benzimidazole, 4-aminopyridine-carbonitrile, pyridopyrimidine, naphthyridine, pyridotriazine