Department of Chemistry, University of York, York, YO10 5DD, UK.
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, China.
Angew Chem Int Ed Engl. 2020 May 4;59(19):7598-7604. doi: 10.1002/anie.202001956. Epub 2020 Mar 11.
The enantioselective intermolecular C2-allylation of 3-substituted indoles is reported for the first time. This directing group-free approach relies on a chiral Ir-(P, olefin) complex and Mg(ClO ) Lewis acid catalyst system to promote allylic substitution, providing the C2-allylated products in typically high yields (40-99 %) and enantioselectivities (83-99 % ee) with excellent regiocontrol. Experimental studies and DFT calculations suggest that the reaction proceeds via direct C2-allylation, rather than C3-allylation followed by in situ migration. Steric congestion at the indole-C3 position and improved π-π stacking interactions have been identified as major contributors to the C2-selectivity.
首次报道了 3-取代吲哚的对映选择性分子间 C2-烯丙基化反应。这种无导向基团的方法依赖于手性 Ir-(P,烯烃)配合物和 Mg(ClO4)路易斯酸催化剂体系来促进烯丙基取代反应，以高收率（40-99%）和对映选择性（83-99%ee）提供 C2-烯丙基化产物，具有出色的区域选择性。实验研究和密度泛函理论（DFT）计算表明，反应通过直接 C2-烯丙基化进行，而不是 C3-烯丙基化后再进行原位迁移。吲哚-C3 位的空间位阻和增强的π-π堆积相互作用被确定为 C2-选择性的主要贡献因素。
