Wang Dinghai, Mück-Lichtenfeld Christian, Studer Armido
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstraße 40, 48149 Münster, Germany.
J Am Chem Soc. 2020 May 20;142(20):9119-9123. doi: 10.1021/jacs.0c03058. Epub 2020 May 6.
A systematic study of radical boron migration in diboronate complexes to form synthetically valuable 1,-bisborylalkanes is reported. The boronate complexes are readily generated by reaction of commercial bis(pinacolato)diboron with alkyl Grignard compounds. C-radical generation at a defined position with respect to the diboron moiety is achieved either via intermolecular H-abstraction with a CF-radical or via alkene perfluoroalkyl radical addition. It is shown that radical 1,2- and 1,4-boron migrations to provide geminal and 1,3-bisborylalkanes are efficient transformations. The 1,5-boron migration in the homologous series leading to 1,4-bisborylalkanes is also occurring, albeit with lower efficiency. Experimental results are supported by DFT calculations which also reveal the corresponding 1,3-boron migration in such diboronate complexes to be feasible.
本文报道了对二硼酸酯配合物中硼自由基迁移以形成具有合成价值的1,1-双硼基烷烃的系统研究。硼酸酯配合物可通过市售的双（频哪醇）二硼与烷基格氏试剂反应轻松生成。相对于二硼部分在特定位置产生碳自由基可通过与CF自由基进行分子间氢原子夺取或通过烯烃全氟烷基自由基加成来实现。结果表明，生成偕二硼基烷烃和1,3-双硼基烷烃的1,2-和1,4-硼自由基迁移是有效的转化反应。导致1,4-双硼基烷烃的同系物系列中的1,5-硼自由基迁移也会发生，尽管效率较低。实验结果得到了DFT计算的支持，该计算还表明此类二硼酸酯配合物中相应的1,3-硼自由基迁移是可行的。
