Regioselective cascade annulation of indoles with alkynediones for construction of functionalized tetrahydrocarbazoles triggered by Cp*RhIII-catalyzed C-H activation

An efficient regioselective and stereoselective cascade annulation of indoles with alkynediones has been demonstrated via a Cp*Rh-III-catalyzed indole C2-H activation by using N-carboamide directing groups in good to excellent yields with a broad substrate scope, which further realized the C2 and C3 difunctionalization of indoles in one-pot. This methodology simultaneously provides a novel and straightforward approach to free (NH) tetrahydrocarbazoles with continuous quaternary carbons and pyridoindolones, which are valuable intermediates in total synthesis of the related indole alkaloids.

Automated summary

This study presents an efficient regioselective and stereoselective cascade annulation of indoles with alkynediones via Cp*Rh-III-catalyzed indole C2-H activation using N-carboamide directing groups, providing valuable intermediates for the total synthesis of related indole alkaloids. The methodology offers a novel and straightforward approach to the synthesis of free (NH) tetrahydrocarbazoles and pyridoindolones with continuous quaternary carbons in good to excellent yields and wide substrate scope, demonstrating the C2 and C3 difunctionalization of indoles in one-pot.