Visible light photoredox catalyzed semisynthesis of the analogues of maclekarpine E: a series of 6-vinyl substituted dihydrobenzophenanthridine alkaloids. Issue 3 (18th October 2017) - Qing, Zhixing
Abstract : A photoredox neutral vinylation of dihydrobenzophenanthridines5 was developed to access the analogue of maclekarpine E (8 ). In this reaction, Ir(ppy)2 (dtbbpy)PF6 was used as a photocatalyst (PC) and α-amino C -radicals6 were the key reactive intermediates. Abstract : A visible light promoted vinylation of N -methyl 5, 6-dihydrobenzophenanthridine was developed to synthesize the analogues of maclekarpine E. In this photoredox neutral radical coupling reaction, an α-amino C -radical generated at the C-6 of N -methyl 5, 6-dihydrobenzophenanthridine was the key intermediate. The subsequent radical addition of vinyl sulfones with the α-amino C -radical followed by elimination of a sulfinyl radical gave the target compounds in moderate to good yields.