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
A General Protocol for C−H Difluoromethylation of Carbon Acids with TMSCF
<sub>2</sub>
Br
作者:Qiqiang Xie、Ziyue Zhu、Lingchun Li、Chuanfa Ni、Jinbo Hu
DOI:10.1002/anie.201900763
日期:2019.5.6
efficient method for the selectiveC‐difluoromethylation of carbon acids with the reagent TMSCF2Br has been developed. A variety of structurally diverse sp3‐ and sp‐hybridized carbon nucleophiles, including esters, amides, fluorenes, terminal alkynes, β‐ketoesters, malonates, and other activated C−H nucleophiles, could be efficiently and selectively transformed into the corresponding C‐difluoromethylated
Highly C-selective difluoromethylation of β-ketoesters by using TMSCF<sub>2</sub>Br/lithium hydroxide/<i>N</i>,<i>N</i>,<i>N</i>-trimethylhexadecan-1-ammonium bromide
作者:Jiandong Wang、Etsuko Tokunaga、Norio Shibata
DOI:10.1039/c8cc05135f
日期:——
The highly C-selective difluoromethylation of β-ketoesters was achieved by combining TMSCF2Br/LiOH/N,N,N-trimethylhexadecan-1-ammonium bromide. Compared to other alkali metal salts or organicbases, lithiumhydroxide, which served as a difluorocarbene activator from TMSCF2Br, was crucial in the control of high C/O regioselectivity.
Inherent Oxygen Preference in Enolate Monofluoromethylation and a Synthetic Entry to Monofluoromethyl Ethers
作者:Yoshinori Nomura、Etsuko Tokunaga、Norio Shibata
DOI:10.1002/anie.201006218
日期:2011.2.18
Expect the unexpected: The self‐stable salts 1, X=OTf, PF6, x=2, y=1, developed for electrophilic monofluoromethylation showed inherent selectivity for the O‐alkylation of enolates, thus providing access to monofluoromethylethers, which are difficult to obtain by the direct electrophilic fluoromethylation of alcohols. Salt 1, X=BF4, x=0, y=3, in contrast leads to C‐alkylated products.
original route to Hu's reagent. Unprecedented chlorofluoromethyl sulfoximines have been also isolated, and these compounds have been shown to act as an electrophilic source of this original bis-halogenated moiety. The mechanism of the electrophilic chlorofluoromethylation is also discussed.