title: Direct C-H functionalization of enamides and enecarbamates by using visible-light photoredox catalysis.
abstract: Direct C-H functionalization of various enamides and enecarbamates was realized through visible-light photoredox catalyzed reactions. Under the optimized conditions using [Ir(ppy)(2)(dtbbpy)PF(6)] as photocatalyst in combination with Na(2)HPO(4), enamides such as N-vinylpyrrolidinone could be easily functionalized by irradiation of the reaction mixture overnight in acetonitrile with visible light. The scope of the reaction with respect to enamide and enecarbamate substrates by using diethyl 2-bromomalonate for the alkylation reaction was explored, followed by an investigation of the scope of alkylating reagents used to react with the enamides and enecarbamates. The results indicated that reaction takes place with quite broad substrate scope, however, tertiary enamides with an internal C=C double bond in the E configuration could not be alkylated. Alkylation of N-vinyl tertiary enamides and enecarbamates gave monoalkylated products exclusively in the E configuration. Alkylation of N-vinyl secondary enamides gave doubly alkylated products. Double bond migration was observed in the reaction of electron-deficient bromides such as 3-bromoacetyl acetate with N-vinylpyrrolidinone. A mechanism is proposed for the reaction that is different from reported reactions of SOMOphiles with a nonfunctionalized C=C double bond. Further tests on the trifluoromethylation and arylation of enamides and enecarbamates under similar conditions showed that the reactions could serve as a mild, practical, and environmentally friendly approach to various functionalized enamides and enecarbamates.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, Institute of Chemical Biology and Drug Innovation, School of Chemistry and Chemical Engineering, Nanjing University, 22 Hankou Road, Nanjing 210093, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Jiang
authors.forename: Chengmei
authors.initials: C
authors.lastname: Huang
authors.forename: Jiajia
authors.initials: J
authors.lastname: Guo
authors.forename: Chuanqi
authors.initials: C
authors.lastname: Zeng
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shouyun
authors.initials: S
authors.lastname: Yu
mesh_terms: D000577:Amides / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D002384:Catalysis; D007495:Iridium / Q000737:chemistry*; D008027:Light; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes
chemical_list: D000577:Amides; D002219:Carbamates; D009942:Organometallic Compounds; D007495:Iridium