Synthesis of <i>N</i>,<i>N</i>'‐Bisindoles via Gold‐Catalyzed Formal (4 + 1) Cycloaddition

Indole‐based heterocycles are commonly found in natural products and pharmaceuticals, so the synthesis of such heterocycles has become an important research area. In spite of the rapid development of this research area, the synthesis of N , N '‐bisindoles remains challenging and is far less developed. Herein, we present the synthesis of N , N '‐bisindoles via gold‐catalyzed formal (4 + 1) cycloaddition of alkynylcyclohexadienones with N ‐aminoindoles, which involves a domino aza –Meyer–Schuster rearrangement/ aza –Michael addition sequence. This reaction allows for the formation of two CN bonds and the direct construction of an indole ring, leading to the synthesis of a range of N , N '‐bisindoles in moderate to high yields with broad functional group tolerance. This work not only provides a new and efficient strategy toward the synthesis of N , N '‐bisindoles but also enriches the research contents of formal (4 + 1) cycloadditions and domino reactions.