Wang Xianjin, Cui Penglei, Xia Chungu, Wu Lipeng
State Key Laboratory for Oxo Synthesis and Selective Oxidation, Suzhou Research Institute of LICP, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences, Lanzhou, 730000, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2021 May 25;60(22):12298-12303. doi: 10.1002/anie.202100569. Epub 2021 Apr 28.
An unprecedented and general titanium-catalyzed boration of alkyl (pseudo)halides (alkyl-X, X=I, Br, Cl, OMs) with borane (HBpin, HBcat) is reported. The use of titanium catalyst can successfully suppress the undesired hydrodehalogenation products that prevail using other transition-metal catalysts. A series of synthetically useful alkyl boronate esters are readily obtained from various (primary, secondary, and tertiary) alkyl electrophiles, including unactivated alkyl chlorides, with tolerance of other reducing functional groups such as ester, alkene, and carbamate. Preliminary studies on the mechanism revealed a possible radical reaction pathway. Further extension of our strategy to aryl bromides is also demonstrated.
报道了一种前所未有的、通用的钛催化烷基（伪）卤化物（烷基-X，X = I、Br、Cl、OMs）与硼烷（HBpin、HBcat）的硼化反应。使用钛催化剂能够成功抑制使用其他过渡金属催化剂时普遍存在的不期望的加氢脱卤产物。一系列具有合成价值的硼酸烷基酯可容易地从各种（伯、仲和叔）烷基亲电试剂中获得，包括未活化的烷基氯，并且对其他还原官能团如酯、烯烃和氨基甲酸酯具有耐受性。对反应机理的初步研究揭示了一种可能的自由基反应途径。还展示了我们的策略对芳基溴化物的进一步拓展。
