甲硅烷基化的氟代烯烃是具有互补反应性的重要合成中间体,在天然产物,药物和人造材料的构造中起关键作用。通过选择性脱氟甲硅烷基化将通常高度稳定的氟代烯烃转化为甲硅烷基化的氟代烯烃是一项艰巨的任务。本文中,我们报道了在烷氧基碱的存在下,各种氟代烯烃与甲硅烷基硼酸酯的简单,廉价和稳健的脱氟甲硅烷基化反应,以直接合成各种甲硅烷基化的氟代烯烃。该协议具有温和而安全的反应条件,可避免催化剂,过渡金属,配体和高反应温度,并能耐受各种氟代烯烃底物,而不会影响效率。N 2'或S N V取代,这是该碱基介导的脱氟甲硅烷基化的原因。
The synthesis of monofluoroalkenes bearing a malonate or its derivatives at the β position is presented. The reaction can be performed with various 3,3-difluoropropenes. A preliminary result for an enantioselective variant is also reported. Further synthetic transformations of a monofluoroalkene were also accomplished.
Fluorinative Rearrangements of Substituted Phenylallenes Mediated by (Difluoroiodo)toluene: Synthesis of α-(Difluoromethyl)styrenes
作者:Zhensheng Zhao、Léanne Racicot、Graham K. Murphy
DOI:10.1002/anie.201706798
日期:2017.9.11
(difluoroiodo)toluene in the presence of 20 mol % BF3⋅OEt2 to yield α‐difluoromethyl styrenes. This unprecedented reaction was entirely chemoselective for the internal allene π bond, and showed remarkable regioselectivity during the fluorination event. Substituted phenylallenes, phenylallenes possessing both phenyl‐ and α‐allenyl substituents, and diphenylallenes were investigated, and good functional‐group
The synthesis of monofluoroalkenes using an SN2′ reaction of lithiumamides derived from aromatic amines or lithium thiolates with 3,3-difluoropropenes is reported. This transformation features the use of fluoride as a leaving group.
The Use of Fluoride as a Leaving Group: SN2′ Displacement of a CF Bond on 3,3-Difluoropropenes with Organolithium Reagents To Give Direct Access to Monofluoroalkenes
Lithium is the key to activate the nucleofuge ability of fluoride in the title transformation (see scheme). This simple and straightforward approach not only provides a practical synthetic method for the preparation of monofluoroalkenes, an important fluorinated motif, but also demonstrates the ability of fluoride to act as a competent leaving group in nucleophilic substitution reactions.
Aluminum-catalyzed tunable halodefluorination of trifluoromethyl- and difluoroalkyl-substituted olefins
作者:Zhong Liu、Xian-Shuang Tu、Le-Tao Guo、Xiao-Chen Wang
DOI:10.1039/d0sc03883k
日期:——
report unprecedented aluminum-catalyzed halodefluorination reactions of trifluoromethyl- and difluoroalkyl-substituted olefins with bromo- or chlorotrimethylsilane. The interesting feature of these reactions is that one, two, or three fluorineatoms can be selectively replaced with bromine or chlorineatoms by modification of the reaction conditions. The generated products can undergo a variety of