The oxazolinone intermediate in the hydrolysis and aminolysis of N-benzoylglycine derivatives

Abstract

The Brønsted type relationship with the pK_a of the departing hydroxy-group for the alkaline hydrolysis (k_OH) of N-benzoylglycine esters exhibits a break consistent with a change in mechanism. Substituted phenyl esters hydrolyse via an oxazolinone intermediate and the high Brønsted selectivity indicates a rate-determining step with considerable C–OAr bond cleavage in its transition state. The formation of the intermediate occurs via a pathway where ionisation of the N-benzoylglycine NH, intramolecular attack, and decomposition of the tetrahedral intermediate are discrete steps. Aminolysis proceeds largely through the ester rather than via the oxazolinone intermediate.