Copper-Catalyzed Sequential C(sp²)-H/C(sp³)-H Annulation of Indoles with Propargylic Alcohols to Access Hydrobenzo[b]carbazoles

Herein, we describe a copper-catalyzed sequential C(sp(2))-H/C(sp(3))-H annulation of indoles with propargylic alcohols for the synthesis of diversely functionalized hydrobenzo[b]carbazole scaffolds. The reaction involves a Friedel-Crafts addition, 1,5-H shift, 6 pi electrocyclization, and dearomatization-aromatization cascade. Importantly, this is a report of the use of 2-(diarylmethyl)indoles as three-carbon synthons in a (3+3) annulation reaction involving C(sp(3))-H indole functionalization under oxidant-free conditions.