Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States.
J Am Chem Soc. 2017 Jun 28;139(25):8404-8407. doi: 10.1021/jacs.7b03986. Epub 2017 Jun 16.
Seven-membered-ring trans-alkenes undergo rapid, uncatalyzed carboboration reactions to form trialkylboranes as single diastereomers. In contrast with other trialkylboranes, which can ignite in the presence of oxygen, these trialkylboranes are stable in air. Hindered trialkylboranes can undergo reverse hydroboration reactions to form allylic silanes or can be oxidized to afford highly substituted triols. This reaction sequence permits the construction of compounds with up to five consecutive stereocenters. Control experiments and computational studies support a concerted mechanism for the migratory insertion of the alkene into the carbon-boron bond, similar to the mechanism for hydroboration.
七元环反式烯烃可快速、无催化地进行碳硼化反应，形成作为单一非对映异构体的三烷基硼烷。与其他可在氧气存在下点燃的三烷基硼烷不同，这些三烷基硼烷在空气中稳定。位阻三烷基硼烷可经反氢硼化反应形成烯丙基硅烷，或可被氧化以得到高取代的三醇。此反应序列可构建多达五个连续的立体中心的化合物。控制实验和计算研究支持烯烃插入碳-硼键的协同迁移插入机理，类似于硼氢化反应的机理。
