Stereochemistry of nucleophilic substitution reaction at a thiophosphoryl centre—IV: Chemical proof of Walden inversion

Abstract

Optically active pyrophosphonothionates (II, III and IV) have been obtained in the reaction between optically active O-ethyl ethylphosphonothioic acid (I) and 2-chloro-2-oxo-5,5-dimethyl-1,3,2-dioxaphosphorinan, diethyl phosphorochloridate and O,O-diethyl phosphorochloridothionate respectively. It has been found that alkaline hydrolysis of these anhydrides occurs with full inversion of configuration at the thiophosphoryl centre. The reaction is discussed from the point of view of stereochemistry and the reaction mechanism.