Stereospecific Transformation of Protected P–H Group into P–O or P–N Group in One-Pot Reaction

A general and efficient procedure for converting 1,1-diethoxyalkylphosphinates
into phosphonates or phosphonamides is described by the application
of bromine with moderate to high yields and good purity in a one-pot
reaction. H-Phosphinate reacts stereospecifically
with bromine and subsequently couples with nucleophile to form the
corresponding optically active R1P­(O)­(OEt)­X with retention
of configuration at the phosphorus center. For α-amino-H-phosphinates, the transformation could be realized without
the protection of the amino group.