Diethyl N,N′-dimethylpyrrol[3,4-f]isoindole-1,7-dicarboxylate as a 14π-electronic aromatic compound with two azomethine-ylide moieties

Abstract Parikh–Doering oxidation of diethyl 9-hydroxy-2,6-dimethyl-4,8-dihydro-4,8-methanopyrrol[3,4- f ]isoindole-1,7-dicarboxylate produced diethyl 9-oxo-2,6-dimethyl-4,8-dihydro-4,8-methanopyrrol[3,4- f ]isoindole-1,7-dicarboxylate. This carbonyl derivative spontaneously underwent cheletropic extrusion of carbon monoxide, producing diethyl 2,6-dimethylpyrrol[3,4- f ]isoindole-1,7-dicarboxylate, which showed 14π-electronic aromaticity on the whole five-six-five ring system.