Unusual transformations of 1-vinyl-4,5,6,7-tetrahydro-5-methyl-4,6- ethanopyrrolo[3,2-c]pyridine to cyclohepteno[b]pyrroles under acetylation conditions

Heating 1-vinyl-4,5,6,7-tetrahydro-5-methyl-4,6-ethanopyrrolo[3,2-c]pyridme (1) in the presence of acetic or trifluoroacetic anhydride resulted in bicyclic saturated fragment cleavage, affording cyclohepteno[b]pyrroles 2a,b in low yields. In the case of trifluoroacetic anhydride, the major product of the reaction, -trifluoroacetylsubstituted tetrahydropyrrolo[3,2-c]pyridine 3 was isolated in 34% yield.