Stereoselective synthesis of (−)-allosedamine and (1R,3R)-HPA-12 from β-p-toluenesulfonamido-γ,δ-unsaturated sulfoxide

A stereoselective synthesis of (−)-allosedamine and HPA-12 is disclosed. The key steps of the synthesis include the diastereoselective synthesis of a β-sulfonamido unsaturated sulfoxide, elaboration of a bromohydrin via intramolecular sulfinyl group participation and a ring-closing metathesis reaction for the construction of the piperidine ring of allosedamine.