Expeditious enantioselective syntheses of (+)-quebrachamine (6),(-)-aspidospermidine (7),(+)-demethoxyaspidospermine (8), and (-)-eburnamonine (9) were accomplished starting from (S)-lactone 1. The syntheses also complete formal, total syntheses of 12 other indole alkaloids of the Aspidosperma and Hunteria types. The key step in the synthesis of (+)- quebrachamine (6) was the Pictet-Spengler condensation of chiral Cg unit 10, derived ...
