Aminolysis and base-catalysed hydrolysis of aryl phenylphosphonamidates and amidothionates: reactions close to the E1cB–bimolecular nucleophilic mechanistic borderline

Abstract

Trapping experiments with amine nucleophiles of high negative Brønsted-type exponent confirm that O-aryl NP-diphenylphosphonamidates [PhPO(NPh)OAr] release phenolate in base via an E1cB process. The corresponding phosphonamidothionates, however, hydrolyse in base via an addition–elimination pathway. These conclusions are consistent with the poorer electron-donating power of the thioanion (P–S^–) compared with oxyanion (P–O^–) to expel phenolate from the corresponding conjugate base [PhPS(Ph)OAr].