Reactions of ketene aminals with N-arylmaleimides and dimethyl acetylenedicarboxylate, a direct pathway to derivatives of pyrrolo[1,2-a] imidazole and imidazo[1,2-a]pyridine

摘要

The addition of N-arylmaleimides or dimethyl acetylenedicarboxylate to 2-imidazolideneacetophenones proceeds at the most nucleophilic carbon atom of the acetophenone derivatives and results in a rearrangement to give derivatives of 5-oxo-2,3,5,6-tetrahydro-1H-pyrrolo[1,2-a]imidazole or imidazo-[1,2-a] pyridine, respectively. In the case of 2-imidazolidenecyclopentanones and 2-imidazolidine-cyclohexanones, the reaction terminates upon the addition of imide or dimethyl acetylenedicarboxylate at the nitrogen atom of the imidazoline system.