Protodeboronation of (Hetero)Arylboronic Esters: Direct versus Prehydrolytic Pathways and Self-/Auto-Catalysis
作者:Hannah L. D. Hayes、Ran Wei、Michele Assante、Katherine J. Geogheghan、Na Jin、Simone Tomasi、Gary Noonan、Andrew G. Leach、Guy C. Lloyd-Jones
DOI:10.1021/jacs.1c06863
日期:2021.9.15
boronic esters under basic aqueous–organic conditions to be highly nuanced. In contrast to common assumption, esterification does not necessarily impart greater stability compared to the corresponding boronic acid. Moreover, hydrolysis of the ester to the boronic acid can be a dominant component of the overall protodeboronation process, augmented by self-, auto-, and oxidative (phenolic) catalysis when
一系列硼酸酯的碱催化水解(ArB(OR) 2 → ArB(OH) 2)和原脱硼化(ArB(OR) 2 → ArH)的动力学和机理,包括八种不同的多元醇和 10 种多氟芳基和杂芳基部分,已通过原位和停流 NMR 光谱(19 F、1 H 和11 B)、pH 速率依赖性、同位素夹带进行了研究,2H KIE 和 KS-DFT 计算。该研究揭示了硼酸酯在碱性水-有机条件下的现象稳定性非常微妙。与通常的假设相反,与相应的硼酸相比,酯化不一定赋予更高的稳定性。此外,酯水解为硼酸可以是整个原脱硼过程的主要成分,当 pH 值接近硼酸的 p K a时,自催化、自催化和氧化(酚类)催化作用增强酯。