For the synthesis of vinyl boronate esters, the direct catalytic H₂-acceptorless dehydrogenative boration of alkenes is one of the promising strategies. In this paper, the density functional theory method was employed to investigate the reaction mechanism of dehydrogenative boration and transfer boration of alkenes catalyzed by a zirconium complex (Cp₂ZrH₂). There are two possible pathways for this reaction: the alkene insertion followed by the dehydrogenative boration (path A) and the alkene insertion after the dehydrogenative boration (path B). The calculated results showed that path A is more favorable than path B, and that the rate-determining step is the C–B coupling step with an energy barrier of 18.7 kcal/mol. The reaction modes of the C–B coupling assisted dehydrogenative boration and the alkene insertion were also discussed. These analyses reveal a novel hydrogen release behavior in dehydrogenative boration and the alkene insertion modes and sequences were proposed to be of importance in the chemoselectivity of this reaction. In addition, the X ligand effect (X = H, Cl) on the catalytic activity of the zirconium complex was explored, indicating that the H ligand could enhance the catalytic activity of the complex for styrene dehydrogenative boration.

中文翻译：

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锆络合物催化烯烃无H2受体脱氢硼化反应的密度泛函理论研究

对于乙烯基硼酸酯的合成，烯烃的直接催化H ₂ -无受体脱氢硼化是有前途的策略之一。本文采用密度泛函理论方法研究了锆络合物(Cp ₂ ZrH _{2 )催化的烯烃脱氢硼酸化和转移硼酸化反应机理。}). 该反应有两种可能的途径：烯烃插入后进行脱氢硼化（路径 A）和烯烃在脱氢硼化后插入（路径 B）。计算结果表明，路径A比路径B更有利，决速步骤为C-B偶联步骤，能垒为18.7 kcal/mol。还讨论了 C-B 偶联辅助脱氢硼化和烯烃插入的反应模式。这些分析揭示了脱氢硼化反应中一种新的氢释放行为，并且提出烯烃插入模式和序列对该反应的化学选择性具有重要意义。此外，探索了 X 配体效应 (X = H, Cl) 对锆络合物催化活性的影响，