Synthesis of pyrrolo[3,4-c]quinoline-1,3-diones: a sequential oxidative annulation followed by dehydrogenation and N-demethylation strategy

A synthetic strategy has been developed for pyrrolo[3,4-c]quinoline-1,3-diones. This synthetic protocol consists of sequential CeO2 catalyzed oxidative annulation followed by DDQ mediated dehydrogenation and N-demethylation. This sequential reaction strategy provides a wide range of fused tetrahydroisoquinolines and pyrrolo[3,4-c]quinoline-1,3-diones in good yields with excellent functional group tolerance. One of the synthesized pyrrolo[3,4-c]quinolines has been unambiguously established by its solid state structure using single crystal XRD. The photophysical properties of the synthesized pyrrolo[3,4-c]quinoline-1,3-diones were evaluated and some of them showed good fluorescence quantum yields.