Tetrabutylammonium phthalimide-N-oxyl: An efficient organocatalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
摘要:
Tetrabutylammonium phthalimide-N-oxyl (TBAPINO) was found to be an effective organocatalyst for rapid, simple and chemoselective protection of the hydroxyl group of alcohols and phenols using hexamethyldisilazane (HMDS) under mild conditions. The low catalyst loading, high to quantitative yields and simple removal of the catalyst from the reaction mixture illustrate the other attractive features of this protocol.
Mechanism of Electrochemical Generation and Decomposition of Phthalimide-<i>N</i>-oxyl
作者:Cheng Yang、Luke A. Farmer、Derek A. Pratt、Stephen Maldonado、Corey R. J. Stephenson
DOI:10.1021/jacs.1c04181
日期:2021.7.14
is a potent hydrogen atom transfer (HAT) catalyst that can be generated electrochemically from N-hydroxyphthalimide (NHPI). However, catalyst decomposition has limited its application. This paper details mechanistic studies of the generation and decomposition of PINO under electrochemical conditions. Voltammetric data, observations from bulk electrolysis, and computational studies suggest two primary
邻苯二甲酰亚胺Ñ -1-氧基(PINO)是可以从电化学可以产生有效的氢原子转移(HAT)催化剂Ñ-羟基邻苯二甲酰亚胺(NHPI)。然而,催化剂分解限制了其应用。本文详细介绍了电化学条件下 PINO 生成和分解的机理研究。伏安数据、大量电解的观察结果和计算研究表明了两个主要方面。首先,碱基促进从 NHPI 形成 PINO 是通过多位点协同质子 - 电子转移(MS-CPET)发生的。其次,PINO 分解发生在至少两个二阶路径中,其中一个通过基数大大增强。PINO 催化氧化的最佳催化效率发生在碱的存在下,该碱的相应共轭酸的 p K a范围为~11-15,这在促进 PINO 形成和最小化其衰变之间取得平衡。