Reactions of alpha-nucleophiles with a model phosphate diester

Abstract

Substantial rate enhancements are observed for the reactions of α-effect nucleophiles with 2,4-dinitrophenyl ethyl phosphate diester 4. The effect is largest (ca. 4500-fold) for the hydroperoxide anion. However, the most reactive α-effect nucleophile, and thus the most reactive nucleophile towards phosphate phosphorus at pHs near to or above its pKa of 13.74, is the hydroxylamine anion NH2O-. The kinetic reactivities of the α-effect nucleophiles follow a Brønsted correlation, with a slope βnuc = 0.41±0.03 greater than that (0.30) observed for non-α- effect nucleophiles, consistent with a thermodynamic origin for the effect. © ARKAT USA, Inc.