1-Oxo-2-oxa-1-phosphabicyclo[2.2.2]octane: A New Mechanistic Probe for the Basic Hydrolysis of Phosphate Esters
作者:Andrzej E. Wróblewski、John G. Verkade
DOI:10.1021/ja9611147
日期:1996.1.1
title compound 2 was accomplished in a multistep sequence starting from hypophosphorous acid. In strong base, the bicyclic phosphinate 2 hydrolyzes 2 orders of magnitude faster than the bicyclic phosphate OP(OCH2)3CCH3 (1a) and the acceleration is entirely enthalpic. This rate enhancement is attributed to the greater ease with which 2 achieves the five-coordinate transition state. The molecular structure
从次磷酸开始以多步顺序完成标题化合物2的合成。在强碱中,双环次膦酸盐 2 的水解速度比双环磷酸盐 OP(OCH2)3CCH3 (1a) 快 2 个数量级,并且加速完全是焓。这种速率提高归因于 2 更容易实现五坐标过渡态。与 1a 相比,通过 X 射线方法确定的 2 的分子结构显示在任一双环框架内都没有应变的迹象。观察到的加速度不支持立体电子效应对六元环磷酸酯水解的贡献。