Total synthesis of clavepictines A and B and pictamine

摘要

A short route for assembling clavepictines A and B and pictamine is described, which features elaboration of its trisubstituted piperidine moiety via condensation of beta-keto sulfone with an L-alanine-derived bromide and subsequent alkylative cyclization and construction of its quinolizidine skeleton via a diastereoselective intramolecular conjugate addition. The possible stereochemical course for this conjugate addition is discussed.