Aziridine-based concise synthesis of (±)-alstonerine.

A concise synthesis of the macroline-related alkaloid (±)-alstonerine is reported. Key steps are regioselective and stereospecific aziridine ring-opening using a sulfone-stabilised carbanion, Me3Al-mediated O → N-transacylation-elimination, intramolecular Michael reaction, and one-pot reduction-dehydration-Pictet-Spengler cyclisation.