Generation of α‐Boryl Radicals by H
<sup>.</sup>
Transfer and their Use in Cycloisomerizations
作者:Shicheng Shi、Farbod Salahi、Hunter B. Vibbert、Maleeha Rahman、Scott A. Snyder、Jack R. Norton
DOI:10.1002/anie.202107665
日期:2021.10.11
Carbon-centered radicals can be stabilized by delocalization of their spin density into the vacant p orbital of a boron substituent. α-Vinyl boronates, in particular pinacol (Bpin) derivatives, are excellent hydrogen atom acceptors. Under H2 , in the presence of a cobaloxime catalyst, they generate α-boryl radicals; these species can undergo 5-exo radical cyclizations if appropriate double bond acceptors
以碳为中心的自由基可以通过将其自旋密度离域到硼取代基的空 p 轨道中来稳定。α-乙烯基硼酸酯,特别是频哪醇(Bpin)衍生物,是优异的氢原子受体。在H2下,在钴肟催化剂存在下,它们生成α-硼基自由基;如果存在适当的双键受体,这些物质可以进行 5-exo 自由基环化,从而在 Bpin 上形成带有叔取代基的密集官能化杂环。该反应表现出良好的官能团耐受性和广泛的范围,所得硼酸酯产物可以转化为其他有用的官能团。