Copper-Catalyzed Oxidative Dearomatization/Spirocyclization of Indole-2-Carboxamides: Synthesis of 2‑Spiro-pseudoindoxyls

A copper-catalyzed oxidative dearomatization/spirocyclization of indole-2-carboxamides using tert-butyl hydroperoxide (TBHP) as the oxidant has been developed that provides rapid and efficient access to C2-spiro-pseudoindoxyls. Two of the sp2 C–H bonds are functionalized during the reaction process, and the reaction likely proceeds via the formation of a highly reactive 3H-indol-3-one intermediate followed by aromatic electrophilic substitution with the N-aryl ring of the amide moiety.本研究开发了一种以叔丁基过氧化氢（tert-butyl hydroperoxide, TBHP）为氧化剂的铜催化吲哚-2-甲酰胺类化合物（indole-2-carboxamides）氧化去芳构化/螺环化反应，可快速高效地合成C2-螺环假吲哚酮类衍生物（C2-spiro-pseudoindoxyls）。反应过程中共实现两个sp2杂化碳氢键（sp2 C–H bonds）的官能团化，其反应历程可能为先生成高活性3H-吲哚-3-酮（3H-indol-3-one）中间体，随后经由酰胺片段（amide moiety）的N-芳基环发生芳香亲电取代反应。