Visible-light-initiated tandem synthesis of difluoromethylated oxindoles in 2-MeTHF under additive-, metal catalyst-, external photosensitizer-free and mild conditions

• Published in: Chinese chemical letters Vol. 32; no. 6; pp. 1907 - 1910
• Main Authors: Gui, Qing-Wen, Teng, Fan, Li, Zhou-Chao, Xiong, Zhi-Yuan, Jin, Xue-Feng, Lin, Ying-Wu, Cao, Zhong, He, Wei-Min
• Format: Journal Article
• Language: English
• Published: NEW YORK Elsevier B.V 01.06.2021; Elsevier; College of Chemistry and Materials Science,Hunan Agricultural University,Changsha 410128,China%School of Chemistry and Chemical Engineering,University of South China,Hengyang 421001,China%Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation,Changsha University of Science and Technology,Changsha 410114,China
• Subjects: 2-MeTHF; Chemistry; Chemistry, Multidisciplinary; External photosensitizer-free; Green chemistry; Physical Sciences; Science & Technology; Tandem reaction; Visible light; Visible light; 2-MeTHF; Green chemistry; External photosensitizer-free; Tandem reaction; REAGENTS; RADICAL CASCADE REACTION; N-ARYLACRYLAMIDES; FLUORINATED 3,3-DISUBSTITUTED 2-OXINDOLES; PHOTOCATALYST; ACTIVATED ALKENES; QUINOXALIN-2(1H)-ONES; CYCLIZATION
• ISSN: 1001-8417; 1878-5964
• DOI: 10.1016/j.cclet.2021.01.021

An efficient and eco-friendly protocol for synthesizing difluoromethylated oxindoles through a visible-light-induced one-pot tandem reaction of N-arylacrylamides, difluoroacetic acid and PhI(OAc)2 was developed. This reaction proceeded in the absence of any additive, base, metal-catalyst and external photosensitizer, using cheap CHF2CO2H as a difluoromethylation reagent and bulk biomass-derived 2-MeTHF as a solvent. [Display omitted] An efficient and eco-friendly protocol for synthesizing difluoromethylated oxindoles through a visible-light induced one-pot tandem reaction of N-arylacrylamides, difluoroacetic acid and PhI(OAc)2 was developed. This reaction proceeded in the absence of any additive, base, metal-catalyst and external photosensitizer, using cheap and easily available CHF2CO2H as the difluoromethylation reagent and bulk biomass-derived 2-MeTHF as the sole solvent. 26 Examples of N-arylacrylamide substrates were investigated, and all of them successfully underwent difluoromethylation to deliver the target products in good to excellent yields.