Conversion of a protopine into an indenobenzazepine. Stereoselective formation of cis- and trans-B/C fused indenobenzazepines
Abstract
Treatment of the protopine (7) with strong base and sunlight yields the cis-fused indenobenzazepine (8) while reaction of the oxo-aziridine (9) with acidic reagents leads to the trans-indenobenzazepines (13), (15), and (17), which isomerize with time in the reaction medium to the corresponding cis-analogues (14), (16), and (18).