USE OF 2D-NMR FOR THE ASSIGNMENT OF STRUCTURE OF 1,3,2-OXAZAPHOSPHOLIDIN-2-ONES

Reaction of a chiral amino alcohol with an alkyl phosphorodichloridate gives a mixture of diastereomeric 1,3,2-oxazaphospholidin-2-ones which are epimeric at phosphorus. Analysis by 1D and 2D nmr has shown that it is possible to establish the absolute configuration at phosphorus by nmr techniques. Specifically, stereospecific differences in chemical shifts and NOESY spectra for each isomer are used to establish the absolute stereochemistry at phosphorus for (4R,5S)-2-ethoxy-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidin-2-one diastereomers.