2,3-丁二酮介导的CF3SO2Na与烯烃的氧化三氟甲基化反应

以2,3-丁二酮作为光催化剂, 三氟甲基亚磺酸钠作为三氟甲基化试剂, 在可见光诱导下, 采用温和的反应条件高效地实现了烯烃衍生物的氧化三氟甲基化反应, 以52%~78%的收率合成了22个含有三氟甲基酮类结构的化合物(3a~3v). 该反应的特点是用2,3-丁二酮代替昂贵的金属光催化剂, 在可见光范围内从廉价的三氟甲基化试剂中引发出三氟甲基自由基, 并在氧化剂的协同作用下进行烯烃的氧化三氟甲基化反应.

Oxidative Trifluoromethylation of CF3SO2Na with Olefins Mediated by Diacetyl†

α-Trifluoromethyl ketones have been identified as versatile building blocks for the synthesis of various trifluoromethyl-functionalized molecules. Although there are significant advantages in the development of methods toward direct transformations of styrenes into α-trifluoromethyl ketones, most procedures leading to α-trifluoromethyl ketones require heavy- or transition-metal-based complexes. Herein, a new method was developed for the synthesis of α-trifluoromethyl ketones via diacetyl-catalyzed photooxidative keto-trifluoromethylation of styrenes with sodium trifluorometnanesulfinate(CF₃SO₂Na) under an air atmosphere. Twenty-two α-ketone trifluoromethyl compounds were synthesized in the yields ranging from 52% to 78%. And their structures were characterized by nuclear magnetic resonance spectroscopy(NMR) and gas chromatography-mass spectrometry(GC-MS) analysis. This reaction employed the commercially available, low cost, and easy to handle langloisreagent(CF₃SO₂Na) as a CF₃-radical source, and diacetyl was used as promising low-cost radical initiators to generate CF₃ radicals from sodium trifluorometnanesulfinate efficiently. And the reaction proceeded smoothly to give the products in moderate yield with mild conditions, a simple system and good functional group tolerance. Furthermore, mechanism investigation indicated that the oxidant H₂O₂ played an important role in promoting the photocatalytic cycle process. This photochemical strategy employed diacetyl, instead of expensive metal catalysis, proved to be a greener route to synthesize α-trifluoromethyl ketones compounds.