An unusual cobalt(III)-catalyzed cross-coupling/cyclization of aryl C−H bonds of N-nitrosoanilines with α-diazoβ-ketoesters has been achieved. This protocol features a unique combination of Csp 2 -H activation/Wolff rearrangement process, allowing for the rapid assembly of quaternary 2-oxindoles. The empirical evidence and density functional theory (DFT) calculations reveal the trapping process of transient acceptor ketene intermediates by cobalt metallocycles.

The Rh(III)-catalyzed regioselective C2-H bond carbenoid insertion/cyclization of N-amidoindoles with α-acyl diazo compounds has been developed. This method provides a novel approach to 2H-pyrimido[1,6-a]indol-1-ones with a broad range of functional group tolerance. The synthetic utilities of the approach are demonstrated by versatile chemical transformations.

A Co(III)-catalyzed [4 + 1] cycloaddition of 2-arylpyridines or 2-alkenylpyridines with aldehydes through Csp(2)-H bond activation has been developed. This protocol provides a facile approach to structurally diverse indolizines including benzoindolizines with a broad range of functional group tolerance.

Described herein is the development of an unprecedented approach to direct amination of unstrained aryl-ketone Csp2–Csp2 sigma bonds with sulfonylazides via Rh­(III)-catalyzed Csp2–Csp2 cleavage. This methodology provides an efficient strategy for acyl groups/amino groups switch at the C2-position of indoles in a straightforward fashion. The combination of experimental and computational studies indicates that beta-aryl elimination derived from enole-based cyclorhodiumates is a key step, while the formation of rhodum nitrene is the rate-limiting process.

A Rh(III)-catalyzed carboamination of alkynyl cycloalkanols with arylamines has been developed. This transformation involves a novel Csp-H/Csp-Csp activation relay and provides an efficient approach to versatile 1,2,3-trisubstituted indoles with a broad range of functional group tolerance.