Stereoselective synthesis of P-chiral phosphorus compounds from N-tert-butoxycarbonyl amino acids.

Reaction of the N-t-Boc amino acids alanine and valine with PhPCl(2) gives the P-chiral trans-1,3,2-oxazaphospholidinones exclusively. Variable-temperature NMR and examination of the glycine derivative shows that the isomers observed are due to t-Boc rotation.