Denmark Scott E, Ueki Yusuke
Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, IL 61801.
Organometallics. 2013 Nov 25;32(22). doi: 10.1021/om400582k.
A variety of Lewis bases were combined with 9-BBN-NTf to establish the requirements for the generation of borenium cations. Five different types of behavior were found, but the most interesting was the combination of EtN, DABCO, 2,6-lutidine, or PhP=S which formed borenium ions exclusively even in sub- or superstoichiometric quantities. The 9-BBN borenium ion complex of 2,6-lutidine was found to rapidly catalyze the hydrosilylation of a variety of ketones in the presence of EtSiH. Preliminary mechanistic experiments suggest that the reduction involves borenium ion activation of EtSiH and not the ketone.
将多种路易斯碱与9-硼双环[3.3.1]壬烷-NTf相结合，以确定生成硼正离子的条件。发现了五种不同类型的行为，但最有趣的是乙胺、1,4-二氮杂双环[2.2.2]辛烷、2,6-二甲基吡啶或苯膦硫醚的组合，即使在化学计量以下或以上的量时，也能仅生成硼正离子。发现2,6-二甲基吡啶的9-硼双环[3.3.1]壬烷硼正离子络合物在乙硅烷存在下能快速催化多种酮的硅氢化反应。初步机理实验表明，还原反应涉及乙硅烷的硼正离子活化，而非酮的活化。
