Ir-Catalyzed Reverse Prenylation of 3‑Substituted Indoles: Total Synthesis of (+)-Aszonalenin and (−)-Brevicompanine B

The selective reverse prenylation
of 3-substituted-1H-indoles at C3 is described. The
iridium-catalyzed reaction proceeds
with high branched to linear selectivity (>20:1) for a variety
of
indoles. In addition, a diastereoselective reverse prenylation of
tryptophan methyl ester is disclosed, and its synthetic utility is
demonstrated in the synthesis of (+)-aszonalenin and (−)-brevicompanine
B.