An efficient palladium-catalyzed region-selective C7-trifluoromethylation of indolines using commercially available Umemoto's reagent was reported. The reaction utilizing Umemoto's reagent as CF radical precursor, pyrimidine as a removable directing group, Pd(II) as a catalyst, and Cu(II) as an oxidant furnished the required products with excellent regioselectivities and good yields. The present strategy has good region-selectivity, broad substrate scope, and scale-up application. Additionally, the present method was underlined by the direct C-1 trifluoromethylation of carbazoles. Furthermore, C7 trifluoromethylated indole can also be easily obtained via Pd-catalyzed direct C-7 trifluoromethylation/oxidation/deprotection sequential reactions.
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http://dx.doi.org/10.1021/acs.orglett.3c04123 | DOI Listing |
Org Lett
May 2024
Urumqi Key Laboratory of Green Catalysis and Synthesis Technology, Key Laboratory of Oil and Gas Fine Chemicals, Ministry of Education & Xinjiang Uygur Autonomous Region, State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources, College of Chemistry, Xinjiang University, Urumqi 830017, P. R. China.
An efficient palladium-catalyzed region-selective C7-trifluoromethylation of indolines using commercially available Umemoto's reagent was reported. The reaction utilizing Umemoto's reagent as CF radical precursor, pyrimidine as a removable directing group, Pd(II) as a catalyst, and Cu(II) as an oxidant furnished the required products with excellent regioselectivities and good yields. The present strategy has good region-selectivity, broad substrate scope, and scale-up application.
View Article and Find Full Text PDFBeilstein J Org Chem
January 2024
State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
A visible-light-promoted research protocol for constructing dihydropyrido[1,2-]indolone skeletons is herein described proceeding through a cascade cyclization mediated by trifluoromethyl radicals. This method allows the efficient synthesis of various indole derivatives without the need of photocatalysts or transition-metal catalysts. Mechanism experiments indicate that the process involves a radical chain process initiated by the homolysis of Umemoto's reagent.
View Article and Find Full Text PDFACS Catal
October 2023
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
A cobalt photocatalyst for direct trifluoromethylation of (hetero)arene C(sp)-H bonds is described and shown to operate via visible light activation of a Co-CF intermediate, which functions as a combined chromophore and organometallic reaction center. Chemical oxidations of previously reported (OCO)Co complexes containing a redox-active [OCO] pincer ligand afford a Co-CF complex two oxidation states above Co(II). Computational and spectroscopic studies are consistent with formulation of the product as [(OCO)Co(CF)(THF)(OTf)] () containing an open-shell [OCO] radical ligand bound to a = 0 Co(III) center.
View Article and Find Full Text PDFPhotochem Photobiol Sci
August 2021
Departamento de Ciencias Químicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 954, CP 1113, Buenos Aires, Argentina.
The electron-rich nature of aminoaromatic compounds and the electrophilic character of fluoroalkyl R radicals allow for a special match in substitution reactions. We herein present visible light photocatalyzed fluoroalkylation reactions of aniline derivatives, with a study of the reaction mechanisms. The examples evaluated make use of different photocatalysts, such as polypyridyl complexes of Ir or Ru transition metals, organic dyes such as Rose Bengal, phthalocyanine-metal organocatalysts, or visible-light activated complexes.
View Article and Find Full Text PDFJ Org Chem
August 2021
Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States.
A red-light-mediated Pr-DMQA-catalyzed cascade intramolecular trifluoromethylation and dearomatization of indole derivatives with Umemoto's reagent has been developed. This protocol provides a facile and efficient approach for the construction of functionalized and potentially biologically important CF-containing 3,3-spirocyclic indolines with moderate to high yields and excellent diastereoselectivities under mild conditions. The success of multiple gram-scale (1 and 10 g) experiments further highlights the robustness and practicality of this protocol and the merit of the employment of red light.
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