College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China.
Sci Rep. 2017 Jan 11;7:40491. doi: 10.1038/srep40491.
The origin of the enantio- and regioselectivity of ring-opening reaction of oxabicyclic alkenes catalyzed by rhodium/Josiphos has been examined using M06-2X density functional theory(DFT). DFT calculations predict a 98% ee for the enantioselectivity and only the 1,2-trans product as one regio- and diastereomer, in excellent agreement with experimental results. The solvent tetrahydrofuran(THF) plays a key role in assisting nucleophilic attack. Orbital composition analysis of the LUMO and the NPA atomic charge calculations were conducted to probe the origins of the regioselectivity. The orbital composition analysis reveals two potential electrophilic sites of the Rh-π-allyl intermediate M3 and the NPA atomic charges demonstrate that Cα carries more positive charges than Cγ, which suggests that Cα is the electrophilic site.
采用 M06-2X 密度泛函理论（DFT）研究了手性双膦配体 Josiphos 催化的氧杂环丁烯开环反应的对映选择性和区域选择性的起源。DFT 计算预测对映选择性为 98%ee，且只有 1,2-反式产物作为一个区域和非对映异构体，与实验结果非常吻合。溶剂四氢呋喃（THF）在协助亲核进攻方面起着关键作用。进行了最低空轨道（LUMO）的轨道组成分析和 NPA 原子电荷计算，以探究区域选择性的起源。轨道组成分析揭示了 Rh-π-烯丙基中间体 M3 的两个潜在的亲电位点，NPA 原子电荷表明 Cα 比 Cγ 带更多的正电荷，这表明 Cα 是亲电位点。
