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

• Published in: Journal of the American Chemical Society 2023-03, Vol.145 (8), p.4508-4516
• Main Authors: Peng, Marie, Wang, Chang-Sheng, Chen, Pan-Pan, Roisnel, Thierry, Doucet, Henri, Houk, K. N., Soulé, Jean-François
• Format: Article
• Language: English
• Subjects: Catalysis; Chemical Sciences; Organic chemistry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.2c10932

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 (CpTMP*)­Rh­(III) [CpTMP* = 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.