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 simple protocol for performing chromium-catalyzed highly diastereoselective alkylations of arylmagnesium halides with cyclohexyl iodides at ambient temperature has been developed. Furthermore, this ligand-free CrCl2 enables efficient electrophilic alkenylations of primary, secondary and tetiary alkylmagnesium halides with readily available alkenyl acetates. Moreover, this chemoselective C‒C coupling
Synthesis of 1,4-Diketones from β-Oxo Esters and Enol Acetates by Cerium-Catalyzed Oxidative Umpolung Reaction
作者:Irina Geibel、Jens Christoffers
DOI:10.1002/ejoc.201600057
日期:2016.2
esters are converted with enol acetates in a cerium‐catalyzed, oxidative Umpolung reaction to furnish 1,4‐diketones with up to 95 % yield. Atmospheric oxygen is the oxidant in this process, which can be regarded as ideal from economic and ecological points of view. Further advantages of this new C–C coupling reaction are its operational simplicity and the application of nontoxic and inexpensive CeCl3
A tyrosinase‐mediated arylation reaction is presented. Starting from a variety of substituted phenols, the enzyme generates activated o‐quinones, which subsequently can undergo a 1,4‐addition towards the desired arylation products, processing a quaternary center.
Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A
作者:Qiao Li、Chen Zhuang、Donghua Wang、Wei Zhang、Rongxuan Jia、Fengxia Sun、Yilin Zhang、Yunfei Du
DOI:10.3762/bjoc.15.291
日期:——
The construction of the biologically interesting chromone skeleton was realized by PhIO-mediated dehydrogenation of chromanones under mild conditions. Interestingly, this method also found application in the synthesis of the naturally occurring frutinone A.