gem-Difluoroolefination of Diazo Compounds with TMSCF3 or TMSCF2Br: Transition-Metal-Free Cross-Coupling of Two Carbene Precursors

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• 作者：Mingyou Hu ; Chuanfa Ni ; Lingchun Li ; Yongxin Han ; Jinbo Hu
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：November 18, 2015
• 年：2015
• 卷：137
• 期：45
• 页码：14496-14501
• 全文大小：522K
• ISSN：1520-5126

文摘

A new olefination protocol for transition-metal-free cross-coupling of two carbene fragments arising from two different sources, namely, a nonfluorinated carbene fragment resulting from a diazo compound and a difluorocarbene fragment derived from Ruppert鈥揚rakash reagent (TMSCF₃) or TMSCF₂Br, has been developed. This gem-difluoroolefination proceeds through the direct nucleophilic addition of diazo compounds to difluorocarbene followed by elimination of N₂. Compared to previously reported Cu-catalyzed gem-difluoroolefination of diazo compounds with TMSCF₃, which possesses a narrow substrate scope due to a demanding requirement on the reactivity of diazo compounds and in-situ-generated CuCF₃, this transition-metal-free protocol affords a general and efficient approach to various disubstituted 1,1-difluoroalkenes, including difluoroacrylates, diaryldifluoroolefins, as well as arylalkyldifluoroolefins. In view of the ready availability of diazo compounds and difluorocarbene reagents and versatile transformations of 1,1-difluoroalkenes, this new gem-difluoroolefination method is expected to find wide applications in organic synthesis.