Synthesis of (−)-Swainsonine and (−)-8-epi-Swainsonine by the Addition of Allenylmetals to Chiral α,β-Alkoxy Sulfinylimines

The asymmetric synthesis of (-)-swainsonine and (-)-8-epi-swainsonine is reported through the addition of either the allenylzinc or the allenyl lithio cyanocuprate reagents derived from [3-(methoxymethoxy)prop-1-ynyl]trimethylsilane to enantiopure α,β-dialkoxy N-tert-butanesulfinylimines derived from d-erythronolactone.