Asymmetric synthesis of α-amino acids via chiral N-alkylidenesulfinamides

(SR)-(−)-N-[1-(Triethoxymethyl)ethylidene]-p-toluenesulfinamide (2) was synthesized from the addition reaction of triethoxyacetonitrile with MeLi followed by (+)-(R)-d-menthyl p-toluenesulfinate (1R). Sulfinimine 2 underwent complete stereoselective reduction with 9-BBN and addition reaction with allylmagnesium bromide. Optically pure α-amino acids were synthesized from these adducts by simple hydrolysis.