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。
Monofluoroalkenylation of Dimethylamino Compounds through Radical–Radical Cross‐Coupling
作者:Jin Xie、Jintao Yu、Matthias Rudolph、Frank Rominger、A. Stephen K. Hashmi
DOI:10.1002/anie.201602347
日期:2016.8
An unprecedented and challenging radical–radicalcross‐coupling of α‐aminoalkyl radicals with monofluoroalkenyl radicals derived from gem‐difluoroalkenes was achieved. This first example of tandem C(sp3)−H and C(sp2)−F bond functionalization through visible‐light photoredox catalysis offers a facile and flexible access to privileged tetrasubstituted monofluoroalkenes under very mild reaction conditions
Direct Difluoromethylenation of Carbonyl Compounds by Using TMSCF<sub>3</sub>: The Right Conditions
作者:Sankarganesh Krishnamoorthy、Jotheeswari Kothandaraman、Jacqueline Saldana、G. K. Surya Prakash
DOI:10.1002/ejoc.201601038
日期:2016.10
A deoxygenative difluoromethylenation of carbonylcompounds has been developed by using readily available, inexpensive trifluoromethyltrimethylsilane, LiI, and PPh3. The presence of the Li+ ion prevents the unproductive exhaustion of trifluoromethyltrimethylsilane (TMSCF3) by keeping the soluble free fluoride concentration in the reaction medium under control. The strategy of combining solvents to
The hydrodefluorination of CF3-substituted alkenes can be catalyzed by a nickel(II) hydride bearing a pincer ligand. The cata-lyst loading can be as low as 1 mol%. gem-Difluoroalkenes containing a number of functional groups can be formed in good to excellent yields, by a radical mechanism initiated by H• transfer from the nickel hydride. The relative reactivity of various substrates supports the proposed
CF3 取代烯烃的加氢脱氟可以由带有钳状配体的镍 (II) 氢化物催化。催化剂负载量可以低至 1 mol%。通过从氢化镍中转移 H• 引发的自由基机制,可以以良好到极好的产率形成含有许多官能团的 gem-二氟烯烃。各种底物的相对反应性支持所提出的机制,TEMPO 捕获实验也是如此。
A useful magnesium reagent for the preparation of 1,1-difluoro-2-hydroxyphosphonates from diethyl bromodifluoromethylphosphonate via a metal—halogen exchange reaction
When (EtO)2P(O)CF2Br (1) is treated with isopropylmagnesium chloride in THF at low temperature it gives a magnesium species (2) which undergoes reactions with strong electrophiles (HCl, TMSCl, halogens, aldehydes and ketones). The formation of products depends strongly on the reaction conditions. With 1.5 equivalents of 2 between −78 and 0°C, a conversion of more than 90% of aldehydes and ketones into
New Methodology for the Deoxygenative Difluoromethylenation of Aldehydes and Ketones; Unexpected Formation of Tetrafluorocyclopropanes
作者:Ireneusz Nowak、Morris J. Robins
DOI:10.1021/ol047416s
日期:2005.2.1
[GRAPHICS]Generation of difluoromethylene phosphorus ylides in the presence of aldehydes and ketones results in Wittig-type reactions to give gem-difluoroalkenes, Subsequent in situ addition of difluorocarbene (carbenoid) can occur (increased with triphenylphosphine and decreased with tributylphosphine) to give tetrafluorocyclopropanes.