State Key Laboratory for Oxo Synthesis and Selective Oxidation, Center for Excellence in Molecular Synthesis, Lanzhou Institute of Chemical Physics (LICP), University of Chinese Academy of Sciences, Chinese Academy of Sciences, Lanzhou 730000, China.
College of Chemistry, and Institute of Green Catalysis, Zhengzhou University, 100 Science Avenue, Zhengzhou, Henan 450001, China.
J Am Chem Soc. 2022 May 18;144(19):8551-8559. doi: 10.1021/jacs.1c12463. Epub 2022 Apr 4.
A new strategy for the direct cleavage of the C(sp)-OH bond has been developed via activation of free alcohols with neutral diphenyl boryl radical generated from sodium tetraphenylborate under mild visible light photoredox conditions. This strategy has been verified by cross-electrophile coupling of free alcohols and carbon dioxide for the synthesis of carboxylic acids. Direct transformation of a range of primary, secondary, and tertiary benzyl alcohols to acids has been achieved. Control experiments and computational studies indicate that activation of alcohols with neutral boryl radical undergoes homolysis of the C(sp)-OH bond, generating alkyl radicals. After reducing the alkyl radical into carbon anion under photoredox conditions, the following carboxylation with CO affords the coupling product.
通过在温和的可见光照光还原条件下，由四苯硼酸钠生成的中性二苯基硼基自由基来激活游离醇，开发了一种直接裂解 C(sp)-OH 键的新策略。该策略已通过游离醇与二氧化碳的交叉电偶联反应得到验证，从而合成羧酸。已实现一系列伯醇、仲醇和叔醇到酸的直接转化。对照实验和计算研究表明，中性硼基自由基对醇的活化经历 C(sp)-OH 键的均裂，生成烷基自由基。在光还原条件下将烷基自由基还原为碳阴离子后，与 CO 进行后续的羧化反应得到偶联产物。
