Substrate-Controlled Divergent Synthesis of Substituted Carbazoles through Cascade Reaction of 2-Alkenylndoles with α,β-Unsaturated Ketones

Abstract

Substituted carbazoles are valuable N-heterocycles for synthesizing biologically relevant compounds. We established the phosphomolybdic acid/ion liquid-promoted divergent synthesis of substituted carbazoles, leveraging readily available 2-alkenylindoles and unsaturated ketones as starting materials. Switchable product selectivity was achieved using different unsaturated ketones. This protocol features transition-metal-free conditions, a broad substrate scope, and excellent scalability. In addition, a plausible reaction mechanism is proposed based on control and real-time NMR experiments.