title: Bis(difluoromethyl)trimethylsilicate Anion: A Key Intermediate in Nucleophilic Difluoromethylation of Enolizable Ketones with Me3 SiCF2 H.
abstract: A pentacoordinate bis(difluoromethyl)silicate anion, [Me3 Si(CF2 H)2 ](-) , is observed for the first time by the activation of Me3 SiCF2 H 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 Me3 SiCF2 H by using a combination of CsF and 18-crown-6 as the initiation system. Mechanistic investigations demonstrate that [(18-crown-6)Cs](+) [Me3 Si(CF2 H)2 ](-) is a key intermediate in this catalytic reaction.
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Ling-Ling Road, Shanghai, 200032, China.|College of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou, Zhejiang, 318000, China.
authors.forename: Dingben
authors.initials: D
authors.lastname: Chen
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Ling-Ling Road, Shanghai, 200032, China.
authors.forename: Chuanfa
authors.initials: C
authors.lastname: Ni
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Ling-Ling Road, Shanghai, 200032, China.
authors.forename: Yanchuan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Ling-Ling Road, Shanghai, 200032, China.
authors.forename: Xian
authors.initials: X
authors.lastname: Cai
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Ling-Ling Road, Shanghai, 200032, China.
authors.forename: Xinjin
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Ling-Ling Road, Shanghai, 200032, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Xiao
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Ling-Ling Road, Shanghai, 200032, China. jinbohu@sioc.ac.cn.
authors.forename: Jinbo
authors.initials: J
authors.lastname: Hu
keywords: fluorine; ketones; reaction mechanisms; reactive intermediates; silicates