NMR and X-ray crystallographic studies of axial and equatorial 2-ethoxy-2-oxo-1,4,2-oxazaphosphinane

Condensation of (S)-(N-benzyl)-phenylglycinol with formaldehyde in the presence of diethylphosphite afforded hydroxyaminophosphonate , which upon treatment with KH yielded a 97:3 mixture of the interesting, phosphorus-containing 2-ethoxy-2-oxo-1,4,2-oxazaphosphinanes and . Suitable crystals of both diastereomers were used in X-ray crystallographic studies that permitted unequivocal configurational assignment, as well as examination of the consequences of nO→σP–O∗ stereoelectronic interactions on structural properties.