A general asymmetric synthesis of syn- and anti-β-Substituted cysteine and serine derivatives

A stereodivergent synthetic route has been developed to make the optically pure anti- and syn-β-substituted cysteine and serine derivatives. In this approach, the key intermediates, > 94% enantiomerically pure cyclic sulfates 3 and aziridines 7, were prepared from α,β-unsaturated esters 1, employing the Sharpless asymmetric dihydroxylation. The high regio- and stereoselective ring-opening reactions of cyclic sulfates and aziridines provided enantiomerically pure β-substituted cysteine and serine derivatives.