- Synthesis conditions and activity of various Lewis acids for the fluorination of trichloromethoxy-benzene by HF in liquid phase
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The experimental conditions (temperature, reaction time, amount of hydrogen fluoride (HF)) for the comparison of the performances of various Lewis acids in the liquid phase fluorination by HF of the trichloromethoxy-benzene were determined by using SbCl5 as the reference catalyst. After 1h reaction at 50°C, C6H5OCCl3 was totally converted into C6H5OCF3 requiring only 2mol% of SbCl5 and a stoichiometric amount of HF. The most efficient catalysts were found to be chlorinated Lewis acids in which the metal is at the state of oxidation +V (SbCl5, MoCl5, TaCl5 and NbCl5). The appropriate catalyst has to be able to form a nucleophilic complex with HF, which constitutes the actual fluorinating agent and is more efficient than HF alone.
- Salomé,Mauger,Brunet,Schanen
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Read Online
- Radical Hydrodehalogenation of Aryl Halides with H2 Catalyzed by a Phenanthroline-Based PNNP Cobalt(I) Complex
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Radical hydrodehalogenation of aryl halides (Ar-X; X = Cl, Br, I) is achieved in the presence of atmospheric pressure H2 as a H-atom donor using a Co(I) catalyst bearing a phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline). The reaction proceeds under mild conditions (1 atm H2) and is applicable to aryl bromides and aryl chlorides with various functional groups. A mechanistic study revealed that the PNNP-Co complex underwent facile H-H cleavage and facilitated a H-atom transfer. This process is mediated by a long-range metal-ligand cooperation of the PNNP-Co system, which includes the dearomatization/aromatization sequence of the phenanthroline ligand backbone. A radical clock experiment demonstrated the Ar-X bond cleavage via a radical mechanism. Further kinetic study supported that the rate-determining step includes electron transfer from the Co center to the substrate, affording a radical pair ArX?- and an odd-electron metal-halide complex [Co(II) + ArX?-]? as a transition state.
- Iizuka, Kosuke,Ishizaka, Yusuke,Jheng, Nai-Yuan,Minami, Yasunori,Naganawa, Yuki,Nakajima, Yumiko,Sekiguchi, Akira
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p. 2320 - 2329
(2022/02/16)
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- Electrochemical Activation of Diverse Conventional Photoredox Catalysts Induces Potent Photoreductant Activity**
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Herein, we disclose that electrochemical stimulation induces new photocatalytic activity from a range of structurally diverse conventional photocatalysts. These studies uncover a new electron-primed photoredox catalyst capable of promoting the reductive cleavage of strong C(sp2)?N and C(sp2)?O bonds. We illustrate several examples of the synthetic utility of these deeply reducing but otherwise safe and mild catalytic conditions. Finally, we employ electrochemical current measurements to perform a reaction progress kinetic analysis. This technique reveals that the improved activity of this new system is a consequence of an enhanced catalyst stability profile.
- Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.
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p. 21418 - 21425
(2021/08/25)
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- Radical C?H Trifluoromethoxylation of (Hetero)arenes with Bis(trifluoromethyl)peroxide
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Trifluoromethoxylated (hetero)arenes are of great interest for several disciplines, especially in agro- and medicinal chemistry. Radical C?H trifluoromethoxylation of (hetero)arenes represents an attractive approach to prepare such compounds, but the high cost and low atom economy of existing .OCF3 radical sources make them unsuitable for the large-scale synthesis of trifluoromethoxylated building blocks. Herein, we introduce bis(trifluoromethyl)peroxide (BTMP, CF3OOCF3) as a practical and efficient trifluoromethoxylating reagent that is easily accessible from inexpensive bulk chemicals. Using either visible light photoredox or TEMPO catalysis, trifluoromethoxylated arenes could be prepared in good yields under mild conditions directly from unactivated aromatics. Moreover, TEMPO catalysis allowed for the one-step synthesis of valuable pyridine derivatives, which have been previously prepared via multi-step approaches.
- Dix, Stefan,Golz, Paul,Schmid, Jonas R.,Riedel, Sebastian,Hopkinson, Matthew N.
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supporting information
p. 11554 - 11558
(2021/07/09)
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- Direct Trifluoromethylation of Alcohols Using a Hypervalent Iodosulfoximine Reagent
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The direct trifluoromethylation of a variety of aliphatic alcohols using a hypervalent iodosulfoximine reagent afforded the corresponding ethers in moderate to good yields (14–72 %). Primary, secondary, and even tertiary alcohols, including examples derived from natural products, underwent this transformation in the presence of catalytic amounts of zinc bis(triflimide). Typical reaction conditions involved a neat mixture of 6.0 equivalents of the alcohol with 1.0 equivalent of the reagent, with the majority of reactions complete within 2 h with 2.5 mol % of the Lewis acid catalyst. Furthermore, experimental evidence was provided that the C?O bond-forming process occurred via the coordination of the alcohol to the iodine atom and subsequent reductive elimination.
- Kalim, Jorna,Duhail, Thibaut,Pietrasiak, Ewa,Anselmi, Elsa,Magnier, Emmanuel,Togni, Antonio
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supporting information
p. 2638 - 2642
(2021/01/21)
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- Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow
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The first example of photocatalytic trifluoromethoxylation of arenes and heteroarenes under continuous-flow conditions is described. Application of continuous-flow microreactor technology allowed to reduce the residence time up to 16 times in comparison t
- Cendón, Borja,Gulías, Moisés,Ho, Michelle,No?l, Timothy,Nyuchev, Alexander V.,Sambiagio, Carlo,Struijs, Job J. C.,Wan, Ting,Wang, Ying
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supporting information
p. 1305 - 1312
(2020/07/10)
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- Redox-Neutral TEMPO Catalysis: Direct Radical (Hetero)Aryl C?H Di- and Trifluoromethoxylation
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Applications of TEMPO. catalysis for the development of redox-neutral transformations are rare. Reported here is the first TEMPO.-catalyzed, redox-neutral C?H di- and trifluoromethoxylation of (hetero)arenes. The reaction exhibits a broad substrate scope, has high functional-group tolerance, and can be employed for the late-stage functionalization of complex druglike molecules. Kinetic measurements, isolation and resubjection of catalytic intermediates, UV/Vis studies, and DFT calculations support the proposed oxidative TEMPO./TEMPO+ redox catalytic cycle. Mechanistic studies also suggest that Li2CO3 plays an important role in preventing catalyst deactivation. These findings will provide new insights into the design and development of novel reactions through redox-neutral TEMPO. catalysis.
- Lee, Johnny W.,Lim, Sanghyun,Maienshein, Daniel N.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 21475 - 21480
(2020/10/02)
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- Sequential Xanthalation and O-Trifluoromethylation of Phenols: A Procedure for the Synthesis of Aryl Trifluoromethyl Ethers
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Molecules containing trifluoromethoxyaryl groups are of interest in pharmaceutical, agrochemical, and materials science research, due to their unique physical and electronic properties. Many of the known methods to synthesize aryl trifluoromethyl ethers require harsh reagents and highly controlled reaction conditions and rarely occur when heteroaromatic units are present. The two-step O-trifluoromethylation of phenols via aryl xanthates is one such method that suffers from these drawbacks. Herein, we report a method for the synthesis of aryl trifluoromethyl ethers from phenols by the facile conversion of the phenol to the corresponding aryl and heteroaryl xanthates with newly synthesized imidazolium methylthiocarbonothioyl salts and conversion of these xanthates to the trifluoromethyl ethers under mild reaction conditions.
- Yoritate, Makoto,Londregan, Allyn T.,Lian, Yajing,Hartwig, John F.
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p. 15767 - 15776
(2019/12/04)
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- Silver-Mediated Trifluoromethoxylation of (Hetero)aryldiazonium Tetrafluoroborates
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Here we report a silver-mediated trifluoromethoxylation of (hetero)aryldiazonium tetrafluoroborates by converting an aromatic amino group into an OCF3 group. This method, which can be considered to be a trifluoromethoxylation variation of the classic Sandmeyer-type reaction, uses readily available aryl and heteroaromatic amines as starting materials and AgOCF3 as trifluoromethoxylating reagents. The broad substrate scope and simple, mild reaction condition made this transformation a valuable method in constructing aryl-OCF3 bonds.
- Yang, Yu-Ming,Yao, Jian-Fei,Yan, Wei,Luo, Zhuangzhu,Tang, Zhen-Yu
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supporting information
p. 8003 - 8007
(2019/10/11)
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- DIFLUOROMETHOXYLATION AND TRIFLUOROMETHOXYLATION COMPOSITIONS AND METHODS FOR SYNTHESIZING SAME
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The present invention provides a compound having the structure (I), a processing of making the compound; and a process of using the compound as a reagent for the difluoromethoxylation and trifluoromethoxylation of arenes or heteroarenes.
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Page/Page column 75; 79; 118; 126
(2019/09/18)
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- Visible-Light Photoredox-Catalyzed and Copper-Promoted Trifluoromethoxylation of Arenediazonium Tetrafluoroborates
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We report the development of photoredox-catalyzed and copper-promoted trifluoromethoxylation of arenediazonium tetrafluoroborates, with trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxylation reagent. This new method takes advantage of visible-light photoredox catalysis to generate the aryl radical under mild conditions, combined with copper-promoted selective trifluoromethoxylation. The reaction is scalable, tolerates a wide range of functional groups, and proceeds regioselectively under mild reaction conditions. Furthermore, mechanistic studies suggested that a Cs[Cu(OCF3)2] intermediate might be generated during the reaction.
- Yang, Shaoqiang,Chen, Miao,Tang, Pingping
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supporting information
p. 7840 - 7844
(2019/05/15)
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- Trifluoromethyl aryl sulfonates (TFMS): An applicable trifluoromethoxylation reagent
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Fluorine is probably another favorite hetero-atom for incorporation into small molecules after nitrogen. Among many fluorine-containing groups, trifluoromethyl aryl ethers (ArOCF3) have unique properties in drug design and are difficult to be synthesized, and many different methods were developed to prepare them. A novel one-pot synthesis of o-iodine-aryl trifluoromethyl ethers (ArOCF3I) was described by the reaction of trifluoromethoxylation and iodination with trifluoromethyl aryl sulfonates (TFMS) in this manuscript. The reaction conditions were optimized by screening different solvents, crown ethers, substrates and the ratios and the yields of products were in moderate to high yields (up to 86%).
- Lei, Meng,Miao, Hang,Wang, Xueyuan,Zhang, Wen,Zhu, Chengjian,Lu, Xiaqiang,Shen, Jian,Qin, Yanru,Zhang, Haoyang,Sha, Sijia,Zhu, Yongqiang
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p. 1389 - 1392
(2019/04/30)
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- Redox-Active Reagents for Photocatalytic Generation of the OCF3 Radical and (Hetero)Aryl C?H Trifluoromethoxylation
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The trifluoromethoxy (OCF3) radical is of great importance in organic chemistry. Yet, the catalytic and selective generation of this radical at room temperature and pressure remains a longstanding challenge. Herein, the design and development of a redox-active cationic reagent (1) that enables the formation of the OCF3 radical in a controllable, selective, and catalytic fashion under visible-light photocatalytic conditions is reported. More importantly, the reagent allows catalytic, intermolecular C?H trifluoromethoxylation of a broad array of (hetero)arenes and biorelevant compounds. Experimental and computational studies suggest single electron transfer (SET) from excited photoredox catalysts to 1 resulting in exclusive liberation of the OCF3 radical. Addition of this radical to (hetero)arenes gives trifluoromethoxylated cyclohexadienyl radicals that are oxidized and deprotonated to afford the products of trifluoromethoxylation.
- Zheng, Weijia,Lee, Johnny W.,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 13795 - 13799
(2018/09/27)
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- Radical Trifluoromethoxylation of Arenes Triggered by a Visible-Light-Mediated N?O Bond Redox Fragmentation
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A simple trifluoromethoxylation method enables non-directed functionalization of C?H bonds on a range of substrates, providing access to aryl trifluoromethyl ethers. This light-driven process is distinctly different from conventional procedures and occurs through an OCF3 radical mechanism mediated by a photoredox catalyst, which triggers an N?O bond fragmentation. The pyridinium-based trifluoromethoxylation reagent is bench-stable and provides access to synthetic diversity in lead compounds in an operationally simple manner.
- Jelier, Benson J.,Tripet, Pascal F.,Pietrasiak, Ewa,Franzoni, Ivan,Jeschke, Gunnar,Togni, Antonio
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supporting information
p. 13784 - 13789
(2018/09/14)
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- Catalytic C?H Trifluoromethoxylation of Arenes and Heteroarenes
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The intermolecular C?H trifluoromethoxylation of arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a novel trifluoromethoxylating reagent and redox-active catalysts for the direct (hetero)aryl C?H trifluoromethoxylation. Our approach is operationally simple, proceeds at room temperature, uses easy-to-handle reagents, requires only 0.03 mol % of redox-active catalysts, does not need specialized reaction apparatus, and tolerates a wide variety of functional groups and complex structures such as sugars and natural product derivatives. Importantly, both ground-state and photoexcited redox-active catalysts are effective. Detailed computational and experimental studies suggest a unique reaction pathway where photoexcitation of the trifluoromethoxylating reagent releases the OCF3 radical that is trapped by (hetero)arenes. The resulting cyclohexadienyl radicals are oxidized by redox-active catalysts and deprotonated to form the desired products of trifluoromethoxylation.
- Zheng, Weijia,Morales-Rivera, Cristian A.,Lee, Johnny W.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 9645 - 9649
(2018/03/21)
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- Trifluoromethyl Benzoate: A Versatile Trifluoromethoxylation Reagent
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Trifluoromethyl benzoate (TFBz) is developed as a new shelf-stable trifluoromethoxylation reagent, which can be easily prepared from inexpensive starting materials using KF as the only fluorine source. The synthetic potency of TFBz is demonstrated by trifluoromethoxylation-halogenation of arynes, nucleophilic substitution of alkyl (pseudo)halides, cross-coupling with aryl stannanes, and asymmetric difunctionalization of alkenes. The unprecedented trifluoromethoxylation-halogenation of arynes proceeds smoothly at room temperature with the aid of a crown ether-complexed potassium cation, which significantly stabilizes the trifluoromethoxide anion derived from TFBz.
- Zhou, Min,Ni, Chuanfa,Zeng, Yuwen,Hu, Jinbo
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supporting information
p. 6801 - 6805
(2018/05/31)
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- Fluorodecarboxylation: Synthesis of aryl trifluoromethyl ethers (ArOCF3) and thioethers (ArSCF3)
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Fluorodecarboxylation of aryloxydifluoroacetic acid (ArOCF2CO2H) and arylmercaptodifluoroacetic acid (ArSCF2CO2H) towards ArXCF3 (X = O, S) using silver (I) salts in the presence of Selectfluor in a biphasic system with trifluoroacetic acid additive is discussed.
- Krishanmoorthy, Sankarganesh,Schnell, Simon D.,Dang, Huong,Fu, Fang,Prakash, G.K. Surya
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p. 130 - 135
(2017/09/06)
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- Iron-Catalyzed Isopropylation of Electron-Deficient Aryl and Heteroaryl Chlorides
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Traditional methods for the preparation of secondary alkyl-substituted aryl and heteroaryl chlorides challenge both selectivity and functional group tolerance. This contribution describes the use of statistical design of experiments to develop an effective procedure for the preparation of isopropyl-substituted (hetero)arenes with minimal isopropyl to n-propyl isomerization. The reaction tolerates electronically diverse aryl chloride coupling partners, with excellent conversion observed for strongly electron-deficient aromatic rings, such as esters and amides. Electron-rich systems, including methyl- and methoxy-substituted aryl chlorides, were found to be less reactive. Furthermore, the reaction was found to be most successful when heteroaryl chlorides were submitted to the cross-coupling protocol. By mapping substituent effects on reaction selectivity, we were able to show that electron-deficient aryl chlorides are essential for efficient coupling, and use electronic structure calculations to predict the likelihood of successful coupling through the estimation of the electron affinity of each aryl chloride. Moderate isolated yields were achieved with selected aryl chlorides, and moderate to good isolated yields were obtained for all the heteroaryl chlorides coupled. Excellent selectivity was observed when a 2,6-dichloroquinoline was used, allowing mono-substitution on a challenging substrate. (Figure presented.).
- Sanderson, James N.,Dominey, Andrew P.,Percy, Jonathan M.
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p. 1007 - 1017
(2017/03/27)
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- Production method of trifluoromethoxybenzene
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The invention relates to a production method of an aromatic compound, in particular to a production method of trifluoromethoxybenzene. The production method includes chlorination reaction, fluoridation reaction and product separation and is characterized in that anisole is used as the initial raw material, the chlorination reaction uses aromatic hydrocarbon containing fluorine as the solvent, the solvent cannot be separated after the reaction, the fluoridation reaction of the solvent and HF is performed under proper conditions, the reaction products of the fluoridation reaction are subjected to washing and layering, the lower oil phase is subjected to rectification to obtain the trifluoromethoxybenzene, and the solvent is recycled. The purity of the obtained trifluoromethoxybenzene is larger than 99%, and the yield of the trifluoromethoxybenzene is larger than 95%. The chemical reaction formula is shown as follows.
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Paragraph 0037; 0040-0043; 0047-0050; 0054-0057; 0061-0064
(2017/04/29)
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- PROCESS FOR THE PREPARATION OF 4-SUBSTITUTED-1-(TRIFLUOROMETHOXY)BENZENE COMPOUNDS
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The present invention provides the process for the preparation of 4-substituted-1- (trifluoromethoxy) benzene compounds..
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Page/Page column 7
(2016/09/22)
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- O-Trifluoromethylation of Phenols: Access to Aryl Trifluoromethyl Ethers by O-Carboxydifluoromethylation and Decarboxylative Fluorination
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A new strategy for the synthesis of aryl trifluoromethyl ethers (ArOCF3) by combining O-carboxydifluoromethylation of phenols and subsequent decarboxylative fluorination is reported. This protocol allows easy construction of functionalized trifluoromethoxybenzenes and trifluoromethylthiolated arenes (ArSCF3) in moderate to good yields. Moreover, it utilizes accessible and inexpensive reagents sodium bromodifluoroacetate and SelectFluor II and, thus, is practical for O-trifluoromethylation of phenols. The potential application of this method is demonstrated with the preparation of a plant-growth regulator, Flurprimidol.
- Zhou, Min,Ni, Chuanfa,He, Zhengbiao,Hu, Jinbo
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supporting information
p. 3754 - 3757
(2016/08/16)
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- Xenon Difluoride Mediated Fluorodecarboxylations for the Syntheses of Di- and Trifluoromethoxyarenes
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XeF2 is demonstrated to be a more proficient fluorine-transfer reagent than either NFSI or Selectfluor in fluorodecarboxylations of both mono- and difluoroaryloxy acetic acid derivatives. This method efficiently converts a wide range of neutral and electron-poor substrates to afford the desired di- and trifluoromethyl aryl ethers in good to excellent yields. The purifications are facile, and the reaction times are less than 5 min, which makes these fluorodecarboxylations promising for future PET-imaging applications.
- Chatalova-Sazepin, Claire,Binayeva, Meruyert,Epifanov, Maxim,Zhang, Wei,Foth, Paul,Amador, Carolyn,Jagdeo, Manu,Boswell, Benjamin R.,Sammis, Glenn M.
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p. 4570 - 4573
(2016/09/28)
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- Examples of catalytic and selective routes for fluorinated building blocks
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Examples are presented for the catalytic fluorination of chlorinated starting materials in order to produce building blocks or HFCs. The fluorination of CF3CH2Cl, of CCl2=CCl2, of trichloromethoxylbenzenes and trichloromethoxybenzene involving nucleophilic substitution are reported. In all cases, HF was the fluorinating agent. Depending on the chlorinated substrate and the degree of fluorination required, liquid- or gas-phase processes were involved. Usually, catalysts were SbCl 5 in liquid phase and chromium oxide in gas phase. In the presence of SbCl5, at 90 °C under an initial pressure of 10 bar, the fluorination of CCl2=CCl2 leads mainly to the formation of CClF2CHCl2, and the active catalyst is an antimony mixed halide (SbCl3F2). In the same way, the presence of SbCl5 favored the formation of 1-trifluoromethyl-3- trichloromethylbenzene from bis-1,3-trichloromethylbenzene at low temperature (50 °C) and in the presence of a low amount of HF. Moreover, trichloromethoxybenzene was totally transformed into trifluoromethoxybenzene. At 380 °C and at atmospheric pressure, the transformation of CF 3CH2Cl into CF3CH2F was favored over chromium oxide-based catalyst modified by zinc (corresponding to a (Zn/Zn + Cr) molar ratio of 0.22).
- Brunet, Sylvette
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p. 1067 - 1071
(2014/11/27)
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- Selective fluorination of substituted trichloromethyl benzenes by HF in liquid phase: Preparation of fluorinated building blocks
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The selective fluorination by successive Cl/F exchanges of α,α,α-trichlorotoluene, substituted or not by a chlorine atom, was studied in the presence of HF as the fluorinating agent. The influence of the presence of a catalyst or a basic solvent (such as dioxane, pyridine, tributylphosphate) in order to control the fluorination was also investigated. In mild conditions (50 °C and after 1 h of reaction), HF in excess was required in order to obtained the trifluoromethylation by Cl/F exchanges. The presence of SbCl5 in small amount activated the Cl/F exchanges and only a stoichiometric amount of HF was required whatever the chlorinated molecules. Selective mono and difluorination could be obtained by using basic solvents.
- Piou, Alexandre,Celerier, Stephane,Brunet, Sylvette
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experimental part
p. 1241 - 1246
(2011/01/12)
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- Lability of the trifluoromethyl group of trifluoromethoxybenzenes under HF/Lewis acid conditions
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The trifluoromethyl functionality of trifluoromethoxybenzenes (trifluoromethyl phenyl ethers) becomes labile under HF/Lewis acid conditions. Substrates with an unsubstituted para-position shed their -CF3 groups while performing a Friedel-Crafts reaction upon another substrate molecule's trifluoromethoxy group to generate p-rosolic acids. Substrates that had blocking groups at the para-positions reacted ortho. The electron donating substituents methoxy and phenoxy interfered with the formation of rosolic acids.
- Belter, Randolph K.
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scheme or table
p. 1302 - 1307
(2011/02/22)
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- Kinetics of bromine-magnesium exchange reactions in substituted bromobenzenes
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Competition experiments have been performed to determine the relative reactivities of substituted bromobenzenes, bromonaphthalenes, and 9-bromoanthracene toward i-PrMgCl·;LiCl in THF at 0 °C. The rates of the bromine-magnesium exchange reactions are accelerated by electron-acceptor substituents, the activating efficiency of which increases in the order para 2 = 0.83) with the proton affinities of analogously substituted aryllithiums (slope 0.8). The kinetics of two representative bromoarenes with i-PrMgCl·LiCl were found to be first-order in both bromoarene and i-PrMgCl·LiCl. Combination of the resulting second-order rate constants with the krel values from competition experiments allowed us to calculate reaction times for the bromine-magnesium exchange reactions of a large variety of bromoarenes.
- Shi, Lei,Chu, Yuanyuan,Knoechel, Paul,Mayr, Herbert
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supporting information; experimental part
p. 2760 - 2764
(2009/08/15)
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- METHODS AND COMPOSITIONS FOR PRODUCING DIFLUOROMETHYLENE-AND TRIFLUOROMETHYL-CONTAINING COMPOUNDS
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New methods for producing difluoromethylene-containing compounds with phenylsulfur trifluoride or a primary alkyl-substituted phenylsulfur trifluoride are disclosed. Also, new methods for producing trifluoromethyl-containing compounds with phenylsulfur trifluoride or primary alkyl-substituted phenylsulfur trifluoride are also disclosed.
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Page/Page column 29-30
(2009/07/17)
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- Versatile application of trifluoromethyl triflate
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Hydrolytically stable and easy to handle trifluoromethyl triflate was found to be a liquid reservoir of 'masked' difluorophosgene. Anhydrous F- sources cleave the S-O bond in trifluoromethyl triflate yielding quantitatively the trifluoromethanolate salts, being useful trifluoromethoxy group carriers. Reaction of trifluoromethanolates with in situ generated from o-trimethylsilylphenyl triflate benzyne leads to (trifluoromethoxy)benzene and fluorobenzene (ratio 85:15). Whereas an addition of trifluoromethanethiolate anion across a triple bond of benzyne leads to [(trifluoromethyl)sulfanyl]benzene solely.
- Kolomeitsev, Alexander A.,Vorobyev, Mikhail,Gillandt, Hartmut
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p. 449 - 454
(2008/09/18)
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- CF3 oxonium salts, O-(trifluoromethyl)dibenzofuranium salts: In situ synthesis, properties, and application as a real CF3+ species reagent
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(Chemical Equation Presented) We report in situ synthesis of the first CF3 oxonium salts, thermally unstable O-(trifluoromethyl)- dibenzofuranium salts, which furthermore have different counteranions (BF 4-, PF6-, SbF6 -, and Sb2F11-) and ring substituents (tert-butyl, F, and OCH3), by photochemical decomposition of the corresponding 2-(trifluoromethoxy)biphenylyl-2′- diazonium salts at -90 to -100°C. The yields markedly increased in the order of BF4- 6- 6- 2F11-. The CF3 oxonium salts were fully assigned by means of 1H and 19F NMR spectroscopy at low temperature. The CF3 salts decomposed to form CF4 and dibenzofurans. The half-life times at -60°C of the 2-tert-butyl salts having different counteranions were 29 min for BF4- salt 2d, 36 min for PF6- salt 2c, 270 min for SbF6- salt 2a, and 415 min for Sb2F11- salt 2b. Those at -60°C of the Sb2F11- salts having different 2-substituents were 13 min for F salt 3b, 63 min for H (unsubstituted) salt 1b, and 415 min for tert-butyl salt 2b. Thus, the stability of the CF3 oxonium salts increased in the order of BF4- 6 - 6- 2F 11- and F 3+ species source to the direct O- and N-trifluoromethylations of alcohols, phenols, amines, anilines, and pyridines under very mild conditions. The thermal decomposition method with a mixture of diazonium salt 17a and aryl- or alkylsulfonic acids, pyridine, or pyridines having an electron-withdrawing group also afforded CF3O or CF 3N products. The trifluoromethylation mechanism is discussed and an SN2 mechanism containing the transient formation of free CF 3+ is proposed. Thus, the present study has demonstrated that the exceedingly reactive CF3+ species can be generated much easier than the CH3+ species, contrary to the common sense that CF3+ is extremely difficult to generate in solution.
- Umemoto, Teruo,Adachi, Kenji,Ishihara, Sumi
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p. 6905 - 6917
(2008/02/11)
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- Fluorination agent and preparation and use of same
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The invention disclose a hydrogen fluoride containing composition comprising hydrogen fluoride and a compound which is liquid in the standard state (25° C., 1 atmosphere) and has a boiling point of 120° C. or more and pka of 12 or more at 25° C., and use of the composition for a fluorination agent. The compound which can be preferably used is represented by the formula (1): wherein R1 to R4 are a substituted or unsubstituted alkyl or aryl group and can be the same or different, and R1 or R2 or R3 and R4 can bond to form a ring having a nitrogen atom or a nitrogen atom and other hetero atom, or R1 and R3 can bond to form a ring having a nitrogen atom or a nitrogen atom and other hetero atom. The fluorination agent of the invention exerts effect with a similar reaction mechanism to hydrogen fluoride, can be applied to the halogen exchange reaction of a halogen containing organic compound, and can produce a fluorine containing compound with safety and ease without specific equipment or technique.
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- Process for the dechlorination and/or debromination of fluorine-and chlorine- and/or bromine-containing aromatic compounds
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Fluorine- and chlorine- and/or bromine-containing aromatic compounds are dechlorinated and/or debrominated with hydrogen in an industrially advantageous and selective manner, if the palladium catalyst is present in stationary phase and the aromatic compound in gas phase.
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- Process for the preparation of α-α-α-trifluoroanisoles
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Trifluoroanisoles of the formula STR1 where m is 1 or 2 and n is 0 to 3, are prepared by reacting hydrogen fluoride with trichloroanisoles of the formula STR2 in the vapor phase, in the presence of a fluorinated alumina catalyst wherein X is halogen other than fluorine; R is aryl, preferably 1 to 14 carbon atoms, halogen substituted aryl, halogen, alkyl of 1 to 6 carbon atoms, or alkoxy of 1 to 6 carbon atoms; m is 1 or 2; n is 0 to 3; w is 0 to 2; p is 1 to 3; q is 0 to 2; w+p+q is 3; w' is 1 to 3 and is greater than w; p' is 0 to 2 and is less than p; q' is 0 to 2 and is equal to q; and w'+p'+q' is 3.
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- Fluorination of Aromatic Derivatives with Fluoroxytrifluoromethane and Bis(fluoroxy)difluoromethane
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Fluoroxytrifluoromethane (CF3OF) and bis(fluoroxy)difluoromethane CF2(OF)2 are formed by the reaction of F2 with CO and CO2, respectively, over a CsF catalyst in a continouous-stream process.Both reagents react with aromatic substrates by an electrophilic substitution mechanism to yield fluoro-substituted derivatives.Fluorobenzene is produced in good yield from benzene, and aniline derivatives afford monofluorination products.Acetanilide (1), N-phenylmethanesulfonamide (2), α,α,α-trifluoroacetanilide (3), and 1,1,1-trifluoro(N-phenyl)methanesulfonamide (4) react with either reagent to yield mixtures of o- and p-fluoro-substituted derivatives.Solvent effects and competitive rate experiments demonstrate a preference for ortho substitution, especially in aprotic, nonpolar solvents.With particular substrates, these fluorinating agents are of practical synthetic utility, e.g., 2-fluoro-4-(trifluoromethyl)aniline is produced in high yield by fluorinating the intermediate 4-(trifluoromethyl)acetanilide (6) with CF3OF.Activated substrates such as toluene, xylenes, anisole, and cresols give mixtures of products which reduce the synthetic utility of these reagents.Nitrobenzene is fairly unreactive toward CF3OF and gives low yields of substitution products.
- Fifolt, Michael J.,Olczak, Raymond T.,Mundhenke, Rudolph F.
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p. 4576 - 4582
(2007/10/02)
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- Stable fluorinated sulfuranes and sulfurane oxides. Synthesis and reactions
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Bis(trifluoromethyl) sulfide, tetrafluoro-1,3-dithietane, and bis(trifluoromethyl) sulfoxide undergo oxidative addition when photolyzed with trifluoromethyl hypochlorite to form a new family of sulfuranes, bis(trifluoromethyl)bis(trifluoromethoxy)sulfurane (1) and tetrafluoro-1,3-tetrakis(trifluoromethoxy)dithietane (3), and of sulfurane oxides, bis(trifluoromethyl)bis(trifluoromethoxy)sulfurane oxide (2). Compounds 1 and 2 are hydrolyzed to bis(trifluoromethyl) sulfoxide and bis(trifluoromethyl) sulfone, respectively. Pyrolysis of 1, 2, or 3 gives bis(trifluoromethyl) sulfide, bis(trifluoromethyl) sulfoxide, and tetrafluoro-1,3-dithietane, respectively, plus bis(trifluoromethyl) peroxide. With primary amines, 1 and 2 yield N-alkylbis(trifluoromethyl)sulfimides and sulfoxyimides, and with N,N′-diethylaminotrimethylsilane, imine formation occurs. Sulfurane oxide 2 forms a new type of stable sulfurane oxide (4), bis(trifluoromethyl)bis(hexafluoroisopropylidenimido)sulfurane oxide, with lithium hexafluoroisopropylidenimine. Sulfurane 1 acts in a similar manner with the nucleophile but the sulfurane 5 is not isolated. Compounds 1 and 2 form α,α,α-(trifluoromethyl)anisole derivatives with substituted phenols. Secondary and tertiary alcohols are dehydrated by 1 or 2 to olefins but symmetrical alkyl ethers result when primary alcohols are reacted.
- Kitazume, Tomoya,Shreeve, Jean'ne M.
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p. 2173 - 2176
(2007/10/10)
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