Asymmetric synthesis of phosphonotrifluoroalanine and its derivatives using N- tert-butanesulfinyl imine derived from fluoral

Addition of dialkyl phosphites to ( S)- N- tert-butanesulfinyl imine derived from fluoral afforded, under mild conditions, the corresponding N- tert-butanesulfinyl α-aminophosphonates in moderate to high yields and diastereoselectivity. The major diastereomers of N- tert-butanesulfinyl α-aminophosphonates of ( S S, S) configuration were isolated, and after partial or complete deprotection, converted into enantiomerically pure phosphonotrifluoroalanine and its dialkyl esters.