A highly efficient asymmetric synthesis of β-aminophosphonic acids, via addition of α-phosphonate carbanions to chiral, enantiopure sulfinimines

Addition of α-phosphonate carbanions to (S)-sulfinimines 1 affords N-sulfinyl β-aminophosphonates 2 in a diastereoisomeric ratio from 5:1 to 10:1; the major diastereoisomers of 2, after separation, are converted to the corresponding β-aminophosphonates 3 or to (+)-β-amino-β-phenylethane phosphonic acid 4, whose absolute configuration was established as (R) by X-ray crystallography.