Merging C-H Bond Activation, Alkyne Insertion, and Rearrangements by Rh(III)-Catalysis: Oxindole Synthesis from Nitroarenes and Alkynes

Marie Peng; Chang-Sheng Wang; Pan-Pan Chen; Thierry Roisnel; Henri Doucet; K N Houk; Jean-François Soulé

doi:10.1021/jacs.2c10932

Merging C-H Bond Activation, Alkyne Insertion, and Rearrangements by Rh(III)-Catalysis: Oxindole Synthesis from Nitroarenes and Alkynes

J Am Chem Soc. 2023 Mar 1;145(8):4508-4516. doi: 10.1021/jacs.2c10932. Epub 2023 Feb 20.

Authors

Marie Peng¹, Chang-Sheng Wang¹, Pan-Pan Chen², Thierry Roisnel¹, Henri Doucet¹, K N Houk², Jean-François Soulé¹

Affiliations

¹ Univ Rennes, CNRS UMR6226, Rennes F-3500, France.
² Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States.

PMID: 36802602
DOI: 10.1021/jacs.2c10932

Abstract

We report a Rh(III)-catalyzed ortho-C-H bond functionalization of nitroarenes with 1,2-diarylalkynes and carboxylic anhydrides. The reaction unpredictably affords 3,3-disubstituted oxindoles with the formal reduction of the nitro group under redox-neutral conditions. Besides good functional group tolerance, this transformation allows the preparation of oxindoles with a quaternary carbon stereocenter using nonsymmetrical 1,2-diarylalkynes. This protocol is facilitated by the use of a functionalized cyclopentadienyl (Cp^TMP*)Rh(III) [Cp^TMP* = 1-(3,4,5-trimethoxyphenyl)-2,3,4,5-tetramethylcyclopentadienyl] catalyst we developed, which combines an electron-rich character with an elliptical shape. Mechanistic investigations, including the isolation of three rhodacyle intermediates and extensive density functional theory calculations, indicate that the reaction proceeds through nitrosoarene intermediates via a cascade of C-H bond activation─O-atom transfer─[1,2]-aryl shift─deoxygenation─N-acylation.