Breaking the Trend: Insight into Unforeseen Reactivity of Alkynes in Cobalt-Catalyzed Weak Chelation-Assisted Regioselective C(4)–H Functionalization of 3-Pivaloyl Indole
作者:Shyam Kumar Banjare、Tanmayee Nanda、Bedadyuti Vedvyas Pati、Gopal Krushna Das Adhikari、Juhi Dutta、Ponneri C. Ravikumar
DOI:10.1021/acscatal.1c02689
日期:2021.9.17
chelation-assisted cobalt-catalyzed regioselective C(4)–H activation of 3-pivolyl indole. α-Hydroxy ketone and α,β-unsaturated ketone derivatives have been synthesized in good yields from indole and alkynes. Notably, the indole C(4)–H-functionalized α,β-unsaturated ketone product was obtained with high stereo- and regioselectivity simply by changing the coupling partner from symmetrical alkynes to
通过弱螯合辅助钴催化的区域选择性 C(4)-H 活化 3-pivoyl indole,发现了二苯乙炔的独特反应性。α-羟基酮和α,β-不饱和酮衍生物已经以良好的收率从吲哚和炔烃中合成。值得注意的是,通过将偶联伙伴从对称炔烃变为不对称芳族-脂肪族炔烃,即可获得具有高立体选择性和区域选择性的吲哚 C(4)–H 官能化的 α,β-不饱和酮产物。最重要的是,三氟乙醇是这种转化的唯一水源。从无水三氟乙醇中通过19定量检测双(2,2,2-三氟乙基)醚F NMR 和 LCMS 研究间接证实了水的原位形成。在 HRMS 中检测到六元钴环中间体,而且量子力学计算进一步证实了这一点,这解释了高度区域选择性的 C(4)-H 功能化。