Department of Chemistry and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH) , Pohang, 37673, Republic of Korea.
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon, 34141, Republic of Korea.
J Am Chem Soc. 2017 Jan 18;139(2):976-984. doi: 10.1021/jacs.6b11757. Epub 2016 Dec 30.
A new transition-metal-free borylation of aryl and vinyl halides using 1,1-bis[(pinacolato)boryl]alkanes as boron sources is described. In this transformation one of the boron groups from 1,1-bis[(pinacolato)boryl]alkanes is selectively transferred to aryl and vinyl halides in the presence of sodium tert-butoxide as the only activator to form organoboronate esters. Under the developed borylation conditions, a broad range of organohalides are borylated with excellent chemoselectivity and functional group compatibility, thus offering a rare example of a transition-metal-free borylation protocol. Experimental and theoretical studies have been performed to elucidate the reaction mechanism, revealing the unusual formation of Lewis acid/base adduct between organohalides and α-borylcarbanion, generated in situ from the reaction of 1,1-bis[(pinacolato)boryl]alkanes with an alkoxide base, to facilitate the borylation reactions.
本文描述了一种新型的无过渡金属的芳基和乙烯基卤化物的硼化反应，使用 1,1-双[（频哪醇）硼基]烷烃作为硼源。在这种转化中，1,1-双[（频哪醇）硼基]烷烃中的一个硼基团在叔丁醇钠作为唯一的活化剂存在下，选择性地转移到芳基和乙烯基卤化物中，形成硼酸酯。在开发的硼化条件下，广泛的有机卤化物被硼化，具有优异的化学选择性和官能团兼容性，因此提供了一个罕见的无过渡金属硼化反应方案的例子。进行了实验和理论研究以阐明反应机理，揭示了有机卤化物和α-硼碳负离子之间形成路易斯酸碱加合物的不寻常现象，α-硼碳负离子是由 1,1-双[（频哪醇）硼基]烷烃与烷氧基碱反应原位生成的，以促进硼化反应。
