Cu-Catalyzed [4+1] Annulation toward Indolo[2,1-a]isoquinolines through Oxidative C(sp3 )/C(sp2 )-H Bond Bifunctionalization.

A Cu-catalyzed [4+1] annulation of N-aryl-1,2,3,4-tetrahydroisoquinolines (N-aryl THIQs) with α-diazoketones has been established under oxidative conditions, leading to the construction of a series of indolo[2,1-a]isoquinolines with generally good yields. The reaction enables dediazotized dicarbonylation of α-diazoketones, creating direct C(sp3 )/C(sp2 )-H bond bifunctionalization to access tetracyclic aza-heterocyclic skeletons.