Regiospecific, Enantiospecific Total Synthesis of the 12-Alkoxy-Substituted Indole Alkaloids, (+)-12-Methoxy-N_a-methylvellosimine, (+)-12-Methoxyaffinisine, and (-)-Fuchsiaefoline

摘要

The enantiospecific synthesis of 7-methoxy-D-tryptophan was completed by combination of the Larock heteroannulation process with a Schollkopf-based chiral auxiliary in good yield. This ester was then employed in the first total synthesis of (+)-12-methoxy-N_a-methylvellosimine, (+)-12-methoxyaffinisine, and (-)-fuchsiaefoline in regiospecific, stereospecific fashion in excellent overall yield. The asymmetric Pictet-Spengler reaction and enolate-driven palladium-catalyzed cross coupling processes served as key steps.