Synthesis of Polyazaheterocycles by Michael Addition of CH Acids to α,β-Unsaturated Nitriles. Synthesis of Pyridobenzimidazole and Pyrimidopyridobenzimidazole Derivatives

Article abstract of DOI:10.1002/prac.19933350311

Addition of 1H-benzimidazole-2-carbonitrile (1) to arylidenemalononitrile (2) gave 1-amino-3-aryl pyrido<1,2-a>benzimidazole-2,4-dicarbonitrile (3), 2-aryl-benzimidazole (4) and 1H-benzimidazole-2-acetonitrile, α-(arylmethylene) (5).Compounds (3) reacted with formamide yielding 4-amino-5-aryl pyrimido<5',4':5,6>pyrido<1,2-a>benzimidazole (6).