Monofluoromethyl-Substituted Sulfonium Ylides: Preparation,Structure-ReactivityStudy and Substrate Scope

The Summary of main observation and conclusionStructure-reactivity study of a family of electrophilic monofluoromethylating reagents based on sulfonium ylide skeleton with different steric hindrance and electron-withdrawing properties was described. These studies led us to discover two highly reactive reagents 3 with a cyclic malonate backbone and 6 with an electron-poor 1,1,1,5,5,5-hexafluoropentane-2,4-dione backbone. The high reactivity of reagent 6 allowed to highly selectively access either C-monofluoromethylated or O-monofluoromethylated beta-ketoesters in high yields by the use of different bases. In addition, reactions of reagent 3 with a variety of nucleophiles including phenols, carboxylic acids, thiophenols or heteroaryl nucleophiles occurred in full conversion within 10 min at room temperature and the scopes for these reactions were reported in detail.