AbstractThe hydroboration of CO2 into bis(boryl)acetal (BBA) compounds is an important transformation, since it enabled to selectively reduce CO2 by 4e‐ and to subsequently use the BBA compounds as C1 and Cn sources. However, the influence of the nature of the boryl moieties on the reactivity of BBA compounds has not been evaluated so far. In the present study, four BBA compounds – including two new ones – were reacted with 2,6‐diisopropylaniline to afford the expected imine. Significant differences in the rate of the reaction from minutes to weeks have been observed depending on the BBA used, showing the importance of the nature of the boryl moieties. Theoretical investigations enabled to propose a mechanism involving the addition of the aniline to the BBA as the rate‐determining step and to determine that the steric hindrance of the BBA compounds is the main factor driving the rate of this condensation reaction.
摘要 CO2 与双(硼烷基)缩醛 (BBA) 化合物的氢硼化反应是一种重要的转化过程,因为它能够通过 4e- 选择性地还原 CO2,并随后将 BBA 化合物用作 C1 和 Cn 源。然而,迄今为止还没有评估过硼烷基的性质对 BBA 化合物反应性的影响。在本研究中,四种 BBA 化合物(包括两种新化合物)与 2,6-二异丙基苯胺反应,生成了预期的亚胺。根据所使用的 BBA,反应速度从几分钟到几周都有显著差异,这表明了硼烷基性质的重要性。通过理论研究,我们提出了苯胺与 BBA 的加成机理,这是决定反应速率的一步,并确定 BBA 化合物的立体阻碍是影响缩合反应速率的主要因素。