Synthesis of seven- and eight-membered [1,2-a] alicyclic ring-fused benzimidazoles and 3-aziridinylazepino[1,2-a]benzimidazolequinone as a potential antitumour agent

Azepino and azocino[1,2-a]benzimidazoles were obtained either by treatment of 1-nitrophenyl-2-azacycloalkanes via a one-pot catalytic hydrogenation/acetylation or by treatment of the acetamides generated in the latter reaction with performic acid. This represents the first facile synthesis of eight-membered [1,2-a] alicyclic ring-fused benzimidazoles. 3-Methoxy-azepino[1,2-a]benzimidazole was elaborated to the novel potential cytotoxin, 3-(N-aziridinyl)-7,8,9,10-tetrahydro-6H-azepino[1,2-a]benzimidazole-1,4-dione. The synthesis included clarification of the reactivity of methoxy-substituted benzimidazoles towards nitration.