Synthesis of indolo-quinonediimine derivatives by the thermolysis of 5-(1-benzotriazolyl)-substituted spiro[2 H -benzimidazole-2,1′-cyclohexane]

Abstract

Nucleophilic introduction of the 1H-benzotriazole ring into spiro[2H-benzimidazole-2,1′-cyclohexane] and spiro[2H-imidazo[4,5-b]pyridine-2,1′-cyclohexane], followed by Graebe-Ullmann thermolysis, and also the reduction and formic acid cyclization of five spiro[cyclohexane-1,2′-2′H-imidazo[4,5-b]pyridine] derivatives to give 5-substituted 1H-imidazo[4′,5′:5,6]pyrido[1,2-a]benzimidazoles, are described.