The elimination–addition mechanism of nucleophilic substitution at an alkylphosphonyl centre: stereospecificity, non-stereospecificity and the alkylidineoxophosphorane (phosphene) intermediate

Abstract

The substitution reactions of R′₂CHP(O)(NMeR*)Cl (R′₂CH = fluoren-9-yl; R* = CHMePh) with secondary amines (Me₂NH, Et₂NH, PrⁱNHEt) are largely stereospecific or non-stereospecific depending on the bulk of the amine and its concentration; two elimination–additon pathways, differing in whether or not the phosphene intermediate R′₂CP(O)NMeR* becomes liberated, may be responsible.