Difluoromethylation of some C–H acids with chlorodifluoromethane under conditions of phase transfer catalysis (PTC)
摘要:
Selected C-H acids react with difluorocarbene generated from chlorodifluoromethane with concentrated aqueous solution of sodium hydroxide, and a catalyst, benzyltriethylammonium chloride (TEBAC) in benzene or THF affording C-difluoromethyl substituted derivatives. This process is restricted to C-H acids of pK(a) congruent to 16.3-19.1. The observed facts are rationalized. (C) 2009 Elsevier B.V. All rights reserved.
Air- and Light-Stable <i>S</i>-(Difluoromethyl)sulfonium Salts: <i>C</i>-Selective Electrophilic Difluoromethylation of β-Ketoesters and Malonates
作者:Sheng-Le Lu、Xin Li、Wen-Bing Qin、Jian-Jian Liu、Yi-Yong Huang、Henry N. C. Wong、Guo-Kai Liu
DOI:10.1021/acs.orglett.8b03067
日期:2018.11.2
Air- and light-stable electrophilic difluoromethylating reagents, S-(difluoromethyl)-S-phenyl-S-(2,4,6-trialkoxyphenyl) sulfonium salts were successfully developed, and the introduction of intramolecular hydrogen bonds plays a crucial role for the stabilities and reactivities of these reagents. C-selective difluoromethylation of a broad range of β-ketoesters and malonates proceeded smoothly under mild
highly carbon‐selective difluoromethylation of soft carbon nucleophiles including β‐ketoesters, malonates, oxindoles, benzofuranones and ketenesilylacetals with a difluoromethylated sulfonium ylide under mild conditions was described. Mechanistic studies suggest that these difluoromethylating reactions proceed via a difluorocarbene pathway.