Fang Chang-Zhen, Zhang Bei-Bei, Tu Yong-Liang, Liu Qiang, Wang Zhi-Xiang, Chen Xiang-Yu
School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing National Laboratory for Molecular Sciences, Beijing 100049, China.
Binzhou Institute of Technology, Weiqiao-UCAS Science and Technology Park, Binzhou, Shandong Province 256606, China.
J Am Chem Soc. 2024 Sep 25;146(38):26574-26584. doi: 10.1021/jacs.4c10915. Epub 2024 Sep 12.
The ligated boryl radical (LBR) has emerged as a potent tool for activating alkyl halides in radical transformations through halogen-atom transfer (XAT). However, unactivated alkyl chlorides still present an open challenge for this strategy. We herein describe a new activation mode of the LBR for the activation of unactivated alkyl chlorides to construct a C(sp)-C(sp) bond. Mechanistic studies reveal that the success of the protocol relies on a radical replacement process between the LBR and unactivated alkyl chloride, forming an alkyl borane intermediate as the alkyl radical precursor. Aided with the additive KPO, the alkyl borane then undergoes one-electron oxidation, generating an alkyl radical. The incorporation of the radical replacement activation model to activate unactivated alkyl chlorides significantly enriches LBR chemistry, which has been applied to activate alkyl iodides, alkyl bromides, and activated alkyl chlorides via XAT.
通过卤原子转移（XAT），连接的硼自由基（LBR）已成为自由基转化中活化卤代烃的有力工具。然而，对于该策略而言，未活化的烷基氯仍然是一个有待解决的挑战。我们在此描述了LBR用于活化未活化的烷基氯以构建C(sp)-C(sp)键的一种新的活化模式。机理研究表明，该方法的成功依赖于LBR与未活化的烷基氯之间的自由基取代过程，形成烷基硼烷中间体作为烷基自由基前体。在添加剂KPO的辅助下，烷基硼烷随后进行单电子氧化，生成烷基自由基。引入自由基取代活化模型来活化未活化的烷基氯显著丰富了LBR化学，该化学已被应用于通过XAT活化烷基碘、烷基溴和活化的烷基氯。
