Stereoselectivity, non-stereospecificity, and the lifetime of the thiometaphosphonimidate intermediate formed in the reactions of the diastereoisomers of a phosphonamidothioic chloride with t-butylamine

Abstract

Both diastereoisomers of Bu^tP(S)(Cl)NHR [RNH =(S)-PhMeCHNH] react with Bu^tNH₂(0.25 M) in an aprotic solvent to give the same mixture of the diastereoisomers of Bu^tP(S)(NHBu^t)NHR (no stereospecificity), but the diastereoisomer ratio of the product (stereoselectivity) increases from 57 : 43 (MeCN) to 80 : 20 (cyclohexane) as the polarity (ε_r) of the solvent is reduced.