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Simple and Efficient Generation of Aryl Radicals from Aryl Triflates: Synthesis of Aryl Boronates and Aryl Iodides at Room Temperature

Liu, Wenbo, Yang, Xiaobo, Gao, Yang, Li, Chao-Jun
Journal of the American Chemical Society 2017 v.139 no.25 pp. 8621-8627
ambient temperature, boronic acids, carboxylic acids, diazonium compounds, electron transfer, free radicals, iodides, moieties, organoiodine compounds, phenols, sodium
Despite the wide use of aryl radicals in organic synthesis, current methods to prepare them from aryl halides, carboxylic acids, boronic acids, and diazonium salts suffer from limitations. Aryl triflates, easily obtained from phenols, are promising aryl radical progenitors but remain elusive in this regard. Inspired by the single electron transfer process for aryl halides to access aryl radicals, we developed a simple and efficient protocol to convert aryl triflates to aryl radicals. Our success lies in exploiting sodium iodide as the soft electron donor assisted by light. This strategy enables the scalable synthesis of two types of important organic molecules, i.e., aryl boronates and aryl iodides, in good to high yields, with broad functional group compatibility in a transition-metal-free manner at room temperature. This protocol is anticipated to find potential applications in other aryl-radical-involved reactions by using aryl triflates as aryl radical precursors.