Conversion between Difluorocarbene and Difluoromethylene Ylide
作者:Jian Zheng、Jin-Hong Lin、Ji Cai、Ji-Chang Xiao
DOI:10.1002/chem.201303248
日期:2013.11.4
The interconversion between difluoromethylene ylide and difluorocarbene is described. The difluoromethylene ylideprecursor, Ph3P+CF2CO2−, could be turned into an efficient difluorocarbene reagent, whereas the classical difluorocarbene reagents, HCF2Cl and FSO2CF2CO2TMS, could generate highly reactive difluoromethylene ylide. Thus the Wittig difluoro‐olefination and difluorocyclopropanation could be
描述了二氟亚甲基叶立德和二氟卡宾之间的相互转化。该二氟亚甲基叶立德前体中,Ph 3 P + CF 2 CO 2 - ,也可以变成一个高效的二氟卡宾的试剂,而经典二氟卡宾的试剂,HCF 2 Cl和FSO 2 CF 2 CO 2 TMS,可能会产生高反应性的二氟亚甲基内鎓盐。因此,使用相同的试剂可以选择性地实现Wittig的二氟烯烃化和二氟环丙烷化。另外,从不同卡宾来源获得的叶立德在维蒂希反应中显示出不同的反应性。
Palladium‐Catalyzed Fluoroarylation of
<i>gem</i>
‐Difluoroalkenes
reported. By taking advantage of the in situ generated α-CF3-benzylsilver intermediates derivedfrom the nucleophilic addition of silver fluoride to gem-difluoroalkenes, this strategy bypasses the use of a strong base, thus enabling a mild and general synthetic method for ready access to non-symmetric α,α-disubstituted trifluoroethane derivatives.
A key intermediate, difluoromethylene phosphobetaine, in the Wittig reaction of ClCF2CO2Na–Ph3P with aldehydes was synthesized and characterized, which confirmed the reaction mechanism. The decarboxylation of this stable intermediate was a convenient approach for Wittig difluroolefination. Its reactivity could be adjusted by the modification of the substituent on the phosphorus.
anes are formed from imidazole or thiazole N-oxide, 1,1-difluorostyrene, and an alcohol, amine, or water in a three-component reaction, which probably occurs via 1,3-dipolar cycloaddition. The whole process is a novel method for functionalization of a heterocyclic ring in a position originally occupied by hydrogen. Preliminary experiments show that it occurs for 6-membered N-oxides as well.
Nucleophilic Substitution of <i>gem</i>-Difluoroalkenes with TMSNu Promoted by Catalytic Amounts of Cs<sub>2</sub>CO<sub>3</sub>
作者:Ling-Feng Jiang、Bing-Tao Ren、Bin Li、Guang-Yi Zhang、Yi Peng、Zhen-Yu Guan、Qing-Hai Deng
DOI:10.1021/acs.joc.9b00999
日期:2019.6.7
The efficient and practical nucleophilic cyanation and trifluoromethylation with appropriate trimethylsilyl nucleophiles were developed. Catalytic amounts of cheap and nontoxic Cs2CO3 were used to maintain a sufficiently high concentration of nucleophilic anion (CN– or CF3–) which could begin the catalytic cycle. The present methodologies provide diverse functionalized monofluoroalkenes bearing a cyano
开发了有效和实用的亲核氰化和三氟甲基化反应以及适当的三甲基甲硅烷基亲核试剂。廉价和无毒性的Cs的催化量的2 CO 3被用来维持亲核阴离子(CN的足够高的浓度-或CF 3 - ),其可以开始催化循环。本方法提供了带有氰基和三氟甲基的各种官能化的单氟烯烃,具有优异至中等的立体选择性。