Reactions with thiazole [3,2-a] benzimidazol-3one derivatives: a novel synthesis of pyrano- and pyrido [2,3: 4',5'] thizole [2,3-a] benzimidazole derivatives

A novel synthesis of pyrano-and pyrido[2,3: 4', 5',] thiazolo-[2,3-aJbenzimidazoles via the reaction of malononitrile, ethyl cyanoacetate and cyanoacetamide with 2-arylidene-2,3-dihydrothiazolo [3,2-aJ benzimidazoJ-3-ones is reported. Ring transformation of 4H-pyrans into pyridine derivatives is also reported and discussed