116470-67-8Relevant articles and documents
New Reagent for Highly Efficient Synthesis of Trifluoromethyl-Substituted Arenes and Heteroarenes
Zhang, Xiaomin,Wang, Jian,Wan, Zehong
, p. 2086 - 2089 (2015)
A new reagent trimethylsilyl chlorodifluoroacetate (TCDA) is reported for the introduction of a -CF3 group to arenes and heteroarenes. Compared with current known reagents, TCDA shows very broad scope with respect to electron-deficient, -neutral, and -rich aryl/heteroaryl iodides as well as excellent functional group tolerance, including ester, amide, aldehyde, hydroxyl, and carboxylic acid. (Chemical Equation Presented).
Decarboxylative Trifluoromethylating Reagent [Cu(O2CCF3)(phen)] and Difluorocarbene Precursor [Cu(phen)2][O2CCF2Cl]
Lin, Xiaoxi,Hou, Chuanqi,Li, Haohong,Weng, Zhiqiang
supporting information, p. 2075 - 2084 (2016/02/12)
This article describes the new economic decarboxylative trifluoromethylating reagent [Cu(phen)(O2CCF3)] (1; phen=1,10-phenanthroline) and the efficient difluorocarbene precursor [Cu(phen)2][O2CCF2Cl] (2). Treatment of copper tert-butoxide with phen and subsequent addition of trifluoroacetic acid or chlorodifluoroacetic acid afforded air-stable complexes 1 and 2, respectively, which were characterized by X-ray crystallography. The copper(I) ion in 1 is coordinated by a bidentate phen ligand, a monodentate trifluoroacetate group, and a molecule of CH3CN in a distorted tetrahedral coordination geometry. The molecular structure of 2 adopts an ionic form that consists of a [Cu(phen)2]+ cation and a chlorodifluoroacetate anion. Complex 1 reacted with a variety of aryl and heteroaryl halides to form trifluoromethyl (hetero)arenes in good yields. The corresponding Hammett plot exhibited a linear relationship and a reaction parameter (ρ)=+0.56±0.02, which indicated that the trifluoromethylation reaction proceeded via a nucleophilic reactive species. Complex 2 reacts with phenols to produce aryl difluoromethyl ethers in modest-to-excellent yields. Mechanistic investigations revealed that the difluoromethylation reaction proceeds by initial copper-mediated formation of difluorocarbene and subsequent concerted addition of difluorocarbene to the phenol to form a three-center transition state.
Electron-deficient heteroarenium salts: An organocatalytic tool for activation of hydrogen peroxide in oxidations
?turala, Ji?í,Bohá?ová, Soňa,Chudoba, Josef,Metelková, Radka,Cibulka, Radek
, p. 2676 - 2699 (2015/03/18)
A series of monosubstituted pyrimidinium and pyrazinium triflates and 3,5-disubstituted pyridinium triflates were prepared and tested as simple catalysts of oxidations with hydrogen peroxide, using sulfoxidation as a model reaction. Their catalytic efficiency strongly depends on the type of substituent and is remarkable for derivatives with an electron-withdrawing group, showing reactivity comparable to that of flavinium salts which are the prominent organocatalysts for oxygenations. Because of their high stability and good accessibility, 4-(trifluoromethyl)pyrimidinium and 3,5-dinitropyridinium triflates are the catalysts of choice and were shown to catalyze oxidation of aliphatic and aromatic sulfides to sulfoxides, giving quantitative conversions, high preparative yields and excellent chemoselectivity. The high efficiency of electron-poor heteroarenium salts is rationalized by their ability to readily form adducts with nucleophiles, as documented by low pKR+ values (pKR+ red > -0.5 V). Hydrogen peroxide adducts formed in situ during catalytic oxidation act as substrate oxidizing agents. The Gibbs free energies of oxygen transfer from these heterocyclic hydroperoxides to thioanisole, obtained by calculations at the B3LYP/6-311++g(d,p) level, showed that they are much stronger oxidizing agents than alkyl hydroperoxides and in some cases are almost comparable to derivatives of flavin hydroperoxide acting as oxidizing agents in monooxygenases.
