Peng Marie, Wang Chang-Sheng, Chen Pan-Pan, Roisnel Thierry, Doucet Henri, Houk K N, Soulé Jean-François
Univ Rennes, CNRS UMR6226, Rennes F-3500, France.
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States.
J Am Chem Soc. 2023 Mar 1;145(8):4508-4516. doi: 10.1021/jacs.2c10932. Epub 2023 Feb 20.
We report a Rh(III)-catalyzed -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*)Rh(III) [Cp* = 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─-acylation.
我们报道了一种铑（III）催化的硝基芳烃与1,2-二芳基炔烃和羧酸酐的-C-H键官能团化反应。该反应在氧化还原中性条件下意外地实现了硝基的形式还原，得到3,3-二取代的氧化吲哚。除了良好的官能团耐受性外，这种转化还能使用非对称的1,2-二芳基炔烃制备具有季碳立体中心的氧化吲哚。我们开发的一种功能化环戊二烯基（Cp*）铑（III）[Cp* = 1-(3,4,5-三甲氧基苯基)-2,3,4,5-四甲基环戊二烯基]催化剂促进了该反应，其兼具富电子特性和椭圆形结构。机理研究，包括三种铑环中间体的分离以及广泛的密度泛函理论计算，表明该反应通过亚硝基芳烃中间体，经由C-H键活化、O-原子转移、[1,2]-芳基迁移、脱氧、酰化的级联反应进行。
