Application of the 2-Azaallyl Anion Cycloaddition Method to an Enantioselective Total Synthesis of (+)-Coccinine.

A highly functionalized perhydroindole is formed by the intramolecular [π4s+π2s] cycloaddition of a 2-azaallyl anion with a vinyl sulfide [Eq. (a)]. This is the key step in the total synthesis of (+)-coccinine, the enantiomer of the Amaryllidaceae alkaloid (-)-coccinine.