Reversal of the stereochemical course of the addition of phenylmagnesium bromide to N-benzylimines derived from R-glyceraldehyde depending on the O-protecting group and its application to the synthesis of both enantiomers of phenylglycine

The N-Benzyl imines derived from 2,3-di-O-benzyl-D-glyceraldehyde and 2,3-di-O-isopropylidene-D-glyceraldehyde reacted with phenylmagnesium bromide to afford fully protected aminodiols with total diastereoselectivity. The stereochemical course of the addition reaction depends on the nature of the O-protecting group. These compounds can be easily transformed to enantiomerically pure (R) and (S)alpha-phenylglycine. (C) 1997, Elsevier Science Ltd.