转自：康龙化成
Aryl Boronic Esters Are Stable on Silica Gel and Reactive under Suzuki–Miyaura Coupling Conditions
Naoki Oka, Tsuyoshi Yamada, Hironao Sajiki, Shuji Akai,*and Takashi Ikawa*
Laboratory of Organic Chemistry, Gifu Pharmaceutical University, Gifu 501-1196, Japan
Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, Japan
—Org. Lett. 2022, 24, 3510-3514
Recommended by Shi Li_ MOC
KEYWORDS: carboxylic acids, aldehydes, pinacolborane, triflylpyridinium, reduction
ABSTRACT: A wide range of aryl boronic 1,1,2,2-tetraethylethylene glycol esters [ArB(Epin)s] were readily synthesized. Purifying aryl boronic esters by conventional silica gel chromatography is generally challenging; however, these introduced derivatives are easily purified on silica gel and isolated in excellent yields. We subjected the purified ArB(Epin) to Suzuki–Miyaura couplings, which provided higher yields of the desired biaryl products than those obtained using the corresponding aryl boronic acids or pinacol esters.
Background
Synthesis of ArB(Epin) 2 through the Metalation of Aryl Bromides
Synthesis of ArB(Epin)s 2 through the Dehydrative Esterifications of Boronic Acids
Synthesis of ArB(Epin)s 2 through MiyauraBorylation
Yields of ArB(Epin)s 2 and ArB(pin)s 2′ Obtained by Silica Gel Column Chromatography
Substrate Scope of Borates in Suzuki Coupling
Stabilities of 3-pyridyl BoronicAcids 1k or 2k under Alkaline Conditions
Prof. Shuji Akaiand Takashi Ikawa’s groups reported ArB(Epin)s as stable and easy-to-handle aryl boronates, which can be readily synthesized and purified by column chromatography on silica gel in a manner similar to general organic chemicals. Furthermore, they were directly used to synthesize biaryls using Suzuki−Miyaura coupling chemistry. On the other hand, similar reactions of the corresponding boronic acids or their pinacol esters resulted in lower yields.
Akai Shuji教授和Ikawa Takashi的团队开发了ArB(Epin)s作为稳定且易于使用的芳基硼酸酯，这些芳基硼酸衍生物很容易通过硅胶柱色谱法以类似于一般有机化合物的方式合成和纯化。此外，它们还可直接用于Suzuki−Miyaura偶联反应合成联芳基化合物，而其相应的硼酸或嚬哪醇酯的类似物往往不稳定，导致偶联反应的产率较低。
