Total Synthesis of (+)-Dixiamycin C via a Late-Stage Ni(II)-Photoredox N -Arylation of Carbazoles.

We report the asymmetric total synthesis of dixiamycin C (1) through the shrewd alliance of the naturally occurring monomer xiamycin A methyl ester (5) and its bromo derivative (31) following a late-stage Buchwald-Macmillan's C-N bond formation via a photoredox electron transfer approach with a less reactive carbazole nitrogen. The key step in the synthesis of monomer xiamycin A methyl ester (5) involves Buchwald's Pd(II)-mediated aerobic dehydrogenative C-N bond formation, Beckmann rearrangement, and ipso -acetylation of an electron-rich aromatic ring of an abietane core.