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.