Stereochemical evidence for elimination–addition and a methylenethioxophosphorane (thiophosphene) intermediate in nucleophilic substitution at the PS centre of a benzylic phosphonamidothioic chloride

Abstract

The two diastereoisomers of ArCH₂P(S)(NMeR*)Cl (Ar = 4-NO₂C₆H₄, R* = CHMePh) react with Et₂NH (0.2 mol dm^–3) in CH₂Cl₂ to give mixtures of the diastereoisomers of ArCH₂P(S)(NMeR*)NEt₂ in practically the same ratio (54.5:45.5 or 53:47); such non-stereospecificity points to a thiophosphene intermediate ArCHP(S)NMeR* as the product-forming species.