Theoretical studies to predict the diastereoselectivity of the electrophilicamination of chiral1,3,2-oxazaphospholanes led to the design of (1R), (2S)-1,3-diphenyl-2- (N-isopropylamino)-1-propanol as a powerful chiralauxiliary. The experimental results are in good agreement with the calculations. An efficient synthesis of enantiomerically pure is also reported.