Bis(difluoromethyl)trimethylsilicate Anion: A Key Intermediate in Nucleophilic Difluoromethylation of Enolizable Ketones with Me₃SiCF₂H

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• 作者：Dr. Dingben Chen ; Dr. Chuanfa Ni ; Dr. Yanchuan Zhao ; Xian Cai ; Xinjin Li ; Pan Xiao and Prof. Dr. Jinbo Hu
• 刊名：Angewandte Chemie
• 出版年：2016
• 出版时间：October 4, 2016
• 年：2016
• 卷：128
• 期：41
• 页码：12822-12826
• 全文大小：855K
• ISSN：1521-3757

文摘

A pentacoordinate bis(difluoromethyl)silicate anion, [Me₃Si(CF₂H)₂]⁻, is observed for the first time by the activation of Me₃SiCF₂H with a nucleophilic alkali-metal salt and 18-crown-6. Further study on its reactivity by tuning the countercation effect led to the discovery and development of an efficient, catalytic nucleophilic difluoromethylation of enolizable ketones with Me₃SiCF₂H by using a combination of CsF and 18-crown-6 as the initiation system. Mechanistic investigations demonstrate that [(18-crown-6)Cs]⁺[Me₃Si(CF₂H)₂]⁻ is a key intermediate in this catalytic reaction.