Ten-Step Total Synthesis of (−)-Andranginine

The total synthesis of the indole alkaloid (−)-andranginine has been achieved in 10 steps. Key reactions of the synthesis include a nucleophilic addition of acetylenyl anion to chiral N-sulfinyl imine, an intramolecular N-alkylation reaction to close the C ring, and a dienyne metathesis cascade reaction to construct the DE rings. Meanwhile, 16-epi-(−)-andranginine was also obtained with the developed strategy.