Studies on the chemical reactivity of 1H-benzimidazol-2-ylacetonitrile towards some 3-substituted chromones: synthesis of some novel pyrido[1,2-a]benzimidazoles

A simple and convenient synthesis of a novel series of pyrido[1,2-a]benzimidazoles was efficiently achieved from the condensation reactions of 1H-benzimidazol-2-ylacetonitrile (1) with some 3-substituted chromones, chromone-3-carboxylic acids, chromone-3-carboxamides, ethyl chromone-3-carboxylates and chromone-3-carbonitriles. Reaction of compound 1 with 2-aminochromone-3-carboxaldehydes produced 2-amino-3-(1H-benzimidazol-2-yl)chromeno[2,3-b]pyridines. The reaction mechanisms and spectral data were also discussed.