Complete Switch of Selectivity in the C–H Alkenylation and Hydroarylation Catalyzed by Iridium: The Role of Directing Groups

A complete switch in the Cp*Ir­(III)-catalyzed paths between C–H olefination and hydroarylation was found to be crucially dependent on the type of directing groups. This dichotomy in product distribution was correlated to the efficiency in attaining syn-coplanarity of olefin-inserted 7-membered iridacycles. Theoretical studies support our hypothesis that the degree of flexibility of this key intermediate modulates the β-H elimination, which ultimately affords the observed chemoselectivity.我们发现，在五甲基环戊二烯基铱(III)（Cp*Ir(III)）催化的反应中，C–H烯基化与氢芳基化两条路径的完全切换，关键取决于导向基团的类型。产物分布的这种二分现象，与烯烃插入型七元铱杂环获得顺式共平面构象的效率密切相关。理论研究佐证了我们的假说：该关键中间体的柔性程度可调控β-氢消除过程，最终决定了所观测到的化学选择性。