Divergent Coupling of Benzocyclobutenones with Indoles via C−H and C−C Activations

Highly selective divergent coupling reactions of benzocyclobutenones and indoles, in which the chemoselectivity is controlled by catalysts, are reported herein. The substrates undergo C2(indole)–C8(benzocyclobutenone) coupling to produce benzylated indoles and benzo[b]carbazoles in the Ni‐ and Ru‐catalyzed reactions. A completely different selectivity pattern C2(indole)–C2(benzocyclobutenone) coupling to form arylated indoles is observed in the Rh‐catalyzed reaction. Preliminary mechanistic studies suggest C−H and C−C activations in the reaction pathway. Synthetic utility of this protocol is demonstrated by the selective synthesis of three different types of carbazoles from the representative products. A catalyst‐enabled divergent coupling of benzocyclobutenones with indoles is reported. The divergent reactivity of benzocyclobutenones allows the facile synthesis of three types of valuable indole derivatives, including benzylated indoles, benzo[b]carbazoles, and arylated indoles. This unique divergent coupling will aid in understanding the behaviors of different metal catalysts in C−C bond cleavage and open pathways for the preparation of novel C−C activation systems.