Department of Applied Chemistry, School of Food Science and Biotechnology, Zhejiang Gongshang University , Hangzhou 310035, People's Republic of China.
J Org Chem. 2014 May 16;79(10):4517-27. doi: 10.1021/jo500557w. Epub 2014 May 5.
The mechanisms and origins for the Pd- and Ni-catalyzed regioselective hydrosilylation of allene have been investigated by means of density functional theory (DFT) calculations. The free-energy profiles of Pd- and Ni-catalyzed reactions with small and bulky N-heterocyclic carbene (NHC) ligands are calculated to determine the mechanism for regioselectivities. The calculation results show that different metals (Ni vs Pd) lead to regiochemical reversals for the hydrosilylation of allene. The allylsilane is the major product via palladium catalysis with small NHC ligand, while the vinylsilane is the major product via nickel catalysis with bulky NHC ligand. Both electronic and steric factors play a key role in the regioselectivities for the hydrosilylation of allene via Pd and Ni catalysts. The calculation results are in good agreement with observed regioselectivities and could provide insights into the design of new catalysts for the regioselectivity of hydrosilylation reactions.
通过密度泛函理论（DFT）计算，研究了钯和镍催化的丙二烯区域选择性氢硅烷化反应的机理和起源。计算了具有小体积和大体积 N-杂环卡宾（NHC）配体的钯和镍催化反应的自由能曲线，以确定区域选择性的机理。计算结果表明，不同的金属（Ni 与 Pd）导致丙二烯氢硅烷化反应的区域化学反转。通过小体积 NHC 配体的钯催化，主要产物是烯丙基硅烷，而通过大体积 NHC 配体的镍催化，主要产物是乙烯基硅烷。电子和空间位阻因素在 Pd 和 Ni 催化剂催化的丙二烯氢硅烷化反应的区域选择性中都起着关键作用。计算结果与观察到的区域选择性一致，并为设计新的催化剂以实现氢硅烷化反应的区域选择性提供了思路。
