Directed Fischer Indolization as an Approach to the Total Syntheses of (+)-Aspidospermidine and (-)-Tabersonine.

A conceptually new synthetic approach that provides general access to the aspidosperma alkaloids (+)-aspidospermidine and (-)-tabersonine was developed. This method is based on the regioselective indolization of an ene-hydrazide, which was obtained via a base-catalyzed intramolecular aza-Michael reaction, in situ trapping of the resulting enolate, and subsequent C-N coupling with phenyl hydrazide.