γ-Amino vinyl sulfoxides in asymmetric synthesis. Synthesis of optically pure α-substituted β-amino nitriles

The synthesis of optically pure (E)- and (Z)-γ-amino vinyl sulfoxides derived from commercially available protected α-amino esters is reported. Hydrocyanation of the double bond with Et2AlCN is completely stereoselective and provides enantiomerically pure α-substituted β-amino nitriles with complete control of the configuration at the α-carbon being exerted by the sulfinyl group.