Synthesis of 2-Formyl Carbazoles via Tandem Reaction of Indolyl Nitrones with 2-Methylidene Cyclic Carbonate

The synthesis of functionalized carbazoles as privilegednitrogenheterocycles has emerged as a central topic in drug discovery andmaterial science. We herein disclose the rhodium(III)-catalyzed cross-couplingreaction between indolyl nitrones and 2-methylidene cyclic carbonateas an allylating surrogate, resulting in the formation of C2-formylatedcarbazoles via tandem C-H allylation, [3 + 2] cycloaddition,aromatization, and benzylic oxidation. The synthetic utility of thisprotocol is highlighted by a variety of post-transformations of C2-formylatedcarbazoles.

Automated summary

The synthesis of functionalized carbazoles has become an important topic in drug discovery and material science. In this study, a rhodium(III)-catalyzed cross-coupling reaction between indolyl nitrones and 2-methylidene cyclic carbonate was disclosed, resulting in the formation of C2-formylated carbazoles. The synthetic utility of this protocol was demonstrated by various post-transformations of C2-formylated carbazoles.