Utilization of Protopine and Related Alkaloids. IV. Transformation of Protopine and Protoberberine Alkaloid to Benzo [c] phenan-thridine Alkaloid

Abstract

Anhydroprotopine and anhydromethylberberine were photocyclized to yield 5, 6, 11, 12-tetrahydrobenzo [c] phenanthridine derivatives, which were derived via two steps to sanguinarine and chelerythrine, respectively, in good yield. 5, 6, 11, 12-Tetrahydrobenzo [c]-phenanthridine derivative resulted from the initial photoproduct via rearrangement, which was trapped with dimethyl acetylenedicarboxylate as 4b, 12-etheno-compound.