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.
Chemistry. 2012 Nov 19;18(47):15158-66. doi: 10.1002/chem.201201716. Epub 2012 Sep 27.
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.
通过可见光光氧化还原催化反应，实现了各种烯酰胺和烯基氨基甲酸酯的直接 C-H 功能化。在优化条件下，以[Ir(ppy)(2)(dtbbpy)PF(6)]为光催化剂，结合 Na(2)HPO(4)，在乙腈中用可见光照射反应混合物过夜，可轻松实现 N-乙烯基吡咯烷酮等烯酰胺的功能化。研究了使用二乙基 2-溴丙二酸酯进行烷基化反应时，对烯酰胺和烯基氨基甲酸酯底物的反应范围，并进一步考察了与烯酰胺和烯基氨基甲酸酯反应的烷基化试剂的范围。结果表明，反应具有相当广泛的底物范围，但 E 构型中具有内部 C=C 双键的叔烯酰胺不能被烷基化。N-乙烯基叔烯酰胺和烯基氨基甲酸酯的烷基化反应仅以 E 构型生成单烷基化产物。N-乙烯基仲烯酰胺的烷基化反应得到双烷基化产物。在 3-乙酰基溴乙酸乙酯等缺电子溴化物与 N-乙烯基吡咯烷酮的反应中观察到双键迁移。提出了一种与报道的具有非功能化 C=C 双键的 SOMO 亲核试剂的反应不同的反应机理。在类似条件下对烯酰胺和烯基氨基甲酸酯的三氟甲基化和芳基化的进一步测试表明，该反应可作为一种温和、实用且环保的方法，用于各种功能化的烯酰胺和烯基氨基甲酸酯。
