Asymmetric synthesis of cyclic α-amino phosphonates using masked oxo sulfinimines (N-sulfinyl imines)

Five-, six-, and seven-membered cyclic alpha-amino phosphonates, amino acid surrogates, are prepared in enantiomerically pure form via the highly diastereomeric addition of metal phosphonates to masked oxo sulfinimines. Hydrolysis of the resulting masked oxo alpha-amino phosphonates followed by reduction of the intermediate cyclic imino phosphonates affords the title compounds in good yield.