- Transition-Metal-Free Synthesis of Aryl Trifluoromethyl Thioethers through Indirect Trifluoromethylthiolation of Sodium Arylsulfinate with TMSCF3
-
Herein, we report an indirect trifluoromethylthiolation of sodium arylsulfinates. This transition-metal-free reaction significantly provides an environmentally friendly and practical synthetic method for aryl trifluoromethyl thioethers using commercial Ruppert-Prakash reagent TMSCF3. This approach is also a potential alternative to the current industrial production method owing to facile substrates, excellent functional group compatibility, and operational simplicity.
- Zheng, Changge,Jiang, Chao,Huang, Shuai,Zhao, Kui,Fu, Yingying,Ma, Mingyu,Hong, Jianquan
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supporting information
p. 6982 - 6986
(2021/09/08)
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- Electrochemical Trifluoromethylation of Thiophenols with Sodium Trifluoromethanesulfinate
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We developed an electrochemical trifluoromethylation of thiophenols without the use of metal catalysts and oxidants. This reaction features mild reaction conditions, readily available substrate, as well as moderate to good yields. In addition, this protocol can be easily scaled up with moderate efficiency.
- Zhu, Xing-Xing,Wang, Huai-Qin,Li, Chen-Guang,Xu, Xiao-Lan,Xu, Jun,Dai, Jian-Jun,Xu, Hua-Jian
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p. 16114 - 16120
(2021/02/03)
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- Perfluoroalkylation of Thiosulfonates: Synthesis of Perfluoroalkyl Sulfides
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A practical synthesis of perfluoroalkyl sulfides is described. The method employs stable and readily accessible thiosulfonates as new electrophiles with commercial nucleophilic perfluoroalkylating reagents. The mild reaction conditions allow access to a wide variety of both aryl- and alkyl-substituted perfluoroalkyl sulfides amenable to pharmaceutical development. Furthermore, the reaction operation is straightforward, odorless, does not produce toxic wastes, and, therefore should appeal to practitioners in industrial-scale productions.
- Luo, Ziwei,Yang, Xinkan,Tsui, Gavin Chit
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supporting information
p. 6155 - 6159
(2020/07/30)
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- Transition-Metal-Free ipso-Trifluoromethylthiolation of Lithium Aryl Boronates
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A transition-metal-free direct trifluoromethylthiolation of the ipso-carbon of lithium aryl boronates with trifluoromethanesulfenate under mild conditions was described. In addition, late-stage site-selective C-H borylation/trifluoromethylation and C-Cl b
- Shen, Feng,Zheng, Hanliang,Xue, Xiao-Song,Lu, Long,Shen, Qilong
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p. 6347 - 6351
(2019/08/20)
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- Merging hypervalent iodine and sulfoximine chemistry: A new electrophilic trifluoromethylation reagent
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Electrophilic trifluoromethylation is at the forefront of methodologies available for the installation of the CF3 moiety to organic molecules; research in this field is largely spurred by the availability of stable and accessible trifluoromethy
- Kalim, Jorna,Duhail, Thibaut,Le, Thanh-Nghi,Vanthuyne, Nicolas,Anselmi, Elsa,Togni, Antonio,Magnier, Emmanuel
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p. 10516 - 10523
(2019/12/02)
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- Metal-free trifluoromethylthiolation of arenediazonium salts with Me4NSCF3
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A metal-free entry to the pharmaceutically meaningful substrate class of trifluoromethyl thioethers has been developed starting from widely available arenediazonium salts and commercially available Me4N+SCF3?. This reaction proceeds within one hour at 0 °C and is applicable to a wide range of functionalized substrates.
- Bertoli, Giulia,Exner, Benjamin,Evers, Mathies V.,Tschulik, Kristina,Goo?en, Lukas J.
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p. 132 - 136
(2018/04/05)
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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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- Cu-mediated oxidative trifluoromethylthiolation of arylboronic acids with (bpy)CuSCF3
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An efficient trifluoromethylthiolation reaction of arylboronic acids with (bpy)CuSCF3in the presence of oxygen at room temperature is described. This method produces a variety of aryl trifluoromethylthioether derivatives in good to high yield. The mechanism of this trifluoromethylthiolation is discussed as well.
- Zhao, Mingzhu,Zhao, Xiaoming,Zheng, Purui,Tian, Yawei
-
-
- Silver-catalyzed fluoroalkylation of thiols using fluoroalkanesulfinates
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A practical sliver-catalyzed fluoroalkylation of aryl-, heteroaryl- and alkylthiols has been developed. The reaction has a good functional-group tolerance and excellent selectivity. A variety of stable and solid fluoroalkanesulfinates including di- and perfluoroalkanesulfinates can be employed. This methodology provides a straightforward and streamlined access to perfluoroalkylthiolated organic molecules. [Figure presented]
- Ma, Jing-jing,Liu, Qi-ran,Lu, Guo-ping,Yi, Wen-bin
-
supporting information
p. 113 - 117
(2017/01/03)
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- Copper-Mediated Oxidative Trifluoromethylthiolation of Potassium Aryltrifluoroborates with Elemental Sulfur and Ruppert-Prakash Reagent
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A facile procedure for the copper-mediated oxidative trifluoromethylthiolation of potassium aryl- and heteroaryltrifluoroborates with Ruppert-Prakash reagent and elemental sulfur is presented. Aryl trifluoromethyl thioethers can be prepared in good to mod
- Dubbaka, Srinivas Reddy,Atthunuri, Azmi Reddy,Prakash, Koraboina Chandra,Rangabashyam, Prabhu,Gadde, Satyanarayana,Kothandaraman, Rajesh
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supporting information
p. 1246 - 1252
(2016/05/09)
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- Trifluoromethylthiolation of Unsymmetrical λ3-Iodane Derivatives: Additive-Free, Selective and Scalable Introduction of the SCF3 Group
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The reaction of copper trifluoromethyl sulfide with diaryliodonium salts provides a straightforward pathway for the synthesis of aryl trifluoromethyl thioethers under mild reaction conditions and within short reaction times. High chemoselectivity was achieved by using mesityl as a leaving group. A large range of novel [(het)aryl](mesityl)iodonium salts underwent this reaction under the optimized conditions to give the desired products in moderate to good yields.
- Nikolaienko, Pavlo,Yildiz, Tülay,Rueping, Magnus
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p. 1091 - 1094
(2016/03/05)
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- Sandmeyer-Type Trifluoromethylthiolation and Trifluoromethylselenolation of (Hetero)Aromatic Amines Catalyzed by Copper
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Aromatic and heteroaromatic diazonium salts were efficiently converted into the corresponding trifluoromethylthio- or selenoethers by reaction with Me4NSCF3 or Me4NSeCF3, respectively, in the presence of catalytic amounts of copper thiocyanate. These Sandmeyer-type reactions proceed within one hour at room temperature, are applicable to a wide range of functionalized molecules, and can optionally be combined with the diazotizations into one-pot protocols.
- Matheis, Christian,Wagner, Victoria,Goossen, Lukas J.
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supporting information
p. 79 - 82
(2016/01/25)
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- Trifluoromethylation of thiophenols and thiols with sodium trifluoromethanesulfinate and iodine pentoxide
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A selective and facile trifluoromethylation process for a wide range of thiophenols and thiols under metal free conditions has been developed using two simple and safe solids, sodium trifluoro-methanesulfinate and iodine pentoxide, via the radical process.
- Ma, Jing-Jing,Yi, Wen-Bin,Lu, Guo-Ping,Cai, Chun
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p. 417 - 421
(2016/02/03)
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- Triphenylphosphine-Mediated Deoxygenative Reduction of CF3SO2Na and Its Application for Trifluoromethylthiolation of Aryl Iodides
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We report herein a practical method for taming Langlois' reagent CF3SO2Na to generate CuSCF3 by a triphenylphospine-mediated deoxygenative reduction process. This chemistry highlights a novel utilization of the inherent CF3S skeleton of Langlois' reagent as a CF3S feedstock under mild conditions. The CuSCF3 intermediate generated by this protocol can react with a wide array of supporting ligands to furnish several air-stable [LCu(SCF3)] complexes as valuable trifluoromethylthiolating agents. In addition, the CuSCF3 intermediate can be directly employed for the trifluoromethylthiolation of (hetero)aryl iodides with operational simplicity and atomic efficiency. Efficient synthesis! A low cost method for the generation of CuSCF3 by a triphenylphospine-mediated deoxygenative reduction of Langlois' reagent (CF3SO2Na) has been developed (see scheme). This method can be applied for the convenient synthesis of a wide array of ligated and air-stable CuSCF3 complexes. Additionally, the CuSCF3 complexes generated in situ by this protocol were found to trifluoromethylthiolate (hetero)aryl iodides with high efficiency.
- Yang, Yi,Xu, Long,Yu, Siqi,Liu, Xiaoqiang,Zhang, Yu,Vicic, David A.
-
supporting information
p. 858 - 863
(2016/01/16)
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- Iron-Catalyzed Decarboxylation of Trifluoroacetate and Its Application to the Synthesis of Trifluoromethyl Thioethers
-
Nucleophilic CF3 has been generated by decarboxylation of potassium trifluoroacetate, arguably the most easy-to-handle, inexpensive, and sustainable source of trifluoromethyl groups. Simple iron(II) chloride catalyzes the decarboxylation as well as a subsequent trifluoromethylation of organothiocyanates, resulting in a straightforward synthesis of trifluoromethyl thioethers. The KCN byproduct is absorbed by iron(II) with formation of nontoxic potassium hexacyanoferrate. An analogous trifluoromethylation of aldehydes with trifluoroacetate underlines the synthetic potential of such iron-catalyzed decarboxylative trifluoromethylations.
- Exner, Benjamin,Bayarmagnai, Bilguun,Jia, Fan,Goossen, Lukas J.
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p. 17220 - 17223
(2016/01/25)
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- Copper-Catalyzed Trifluoromethylthiolation of Di(hetero)aryl-λ3-iodanes: Mechanistic Insight and Application to Synthesis of (Hetero)Aryl Trifluoromethyl Sulfides
-
The direct and regioselective copper/S-Phos-catalyzed trifluoromethylthiolation of symmetrical and unsymmetrical di(hetero)aryl-λ3-iodanes has been accomplished for the synthesis of various (hetero)aryl trifluoromethyl sulfides employing readily accessible silver trifluoromethylthiolate (AgSCF3) as nucleophilic trifluoromethylthiolating reagent. The developed transformation tolerates various functional groups like nitrile, enolizable ketone, ester, nitro and free carboxylic acid. Interestingly, the formal trifluoromethylthiolation of arenes was also achieved through integration of the synthesis of diaryl-λ3-iodanes from arenes with the trifluoromethylthiolation. Mechanistic investigations did not favor the radical formation and SET pathway. Based on the variable temperature 19F NMR spectroscopy, isolation of the most relevant catalytic intermediate, and stoichiometric studies supported the Cu(I)/Cu(III) catalytic cycle, wherein the oxidative addition of diaryl-λ3-iodanes was assisted by the silver salt.
- Saravanan, Perumal,Anbarasan, Pazhamalai
-
supporting information
p. 3521 - 3528
(2016/01/25)
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- 18F-Labeling of Aryl-SCF3, -OCF3 and -OCHF2 with [18F]Fluoride
-
We report that halogenophilic silver(I) triflate permits halogen exchange (halex) nucleophilic 18F-fluorination of aryl-OCHFCl, -OCF2Br and -SCF2Br precursors under mild conditions. This AgI-mediated process allows for the first time access to a range of 18F-labeled aryl-OCHF2, -OCF3 and -SCF3 derivatives, inclusive of [18F]riluzole. The 18F-labeling of these medicinally important motifs expands the radiochemical space available for PET applications. A halogen exchange (halex) 18F-fluorination process offers access for the first time to 18F-labeled arylOCF3, arylOCHF2 and arylSCF3, three motifs of established medicinal importance in PET radiotracers. The use of silver(I) triflate is critical to permit 18F-labeling under mild conditions.
- Khotavivattana, Tanatorn,Verhoog, Stefan,Tredwell, Matthew,Pfeifer, Lukas,Calderwood, Samuel,Wheelhouse, Katherine,Leecollier, Thomas,Gouverneur, Vronique
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supporting information
p. 9991 - 9995
(2015/08/19)
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- Mild and Soft Catalyzed Trifluoromethylthiolation of Boronic Acids: The Crucial Role of Water
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The most reactive 2nd generation of trifluoromethanesulfenamides undergoes a copper-catalyzed cross-coupling reaction with boronic acids to afford CF3S-molecules. Contrary to the previous methods in the literature, no base addition, no heating, and no large excess of reagents are required to obtain good results. Furthermore, a crucial role of a small amount of water to favor this reaction has been demonstrated. This constitutes the mildest described conditions for such a reaction.
- Glenadel, Quentin,Alazet, Sébastien,Tlili, Anis,Billard, Thierry
-
supporting information
p. 14694 - 14698
(2015/10/19)
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- Structure-reactivity relationship of trifluoromethanesulfenates: Discovery of an electrophilic trifluoromethylthiolating reagent
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A family of electrophilic trifluoromethanesulfenates was prepared. Structure-reactivity relationship studies showed that the substituted groups on the aryl ring of the trifluoromethylthiolating reagent did not have an obvious influence on their reactivities. A simplified electrophilic trifluoromethylthiolating reagent 1c was then identified that can react with a wide range of nucleophiles such as Grignard reagents, arylboronic acids, alkynes, indoles, β-ketoesters, oxindoles, and sodium sulfinates under mild reaction conditions. A variety of functional groups were tolerated under these conditions.
- Shao, Xinxin,Xu, Chunfa,Lu, Long,Shen, Qilong
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p. 3012 - 3021
(2015/03/30)
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- A mild and fast photocatalytic trifluoromethylation of thiols in batch and continuous-flow
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S-CF3 bonds are important structural motifs in various pharmaceutical and agrochemical compounds. However, their preparation remains a major challenge in synthetic organic chemistry. Here, we report the development of a mild and fast photocatalytic trifluoromethylation of thiols. The combination of commercially available Ru(bpy)3Cl2, visible light and inexpensive CF3I gas proved to be an efficient method for the direct trifluoromethylation of thiols. The protocol is demonstrated on a wide range of aromatic, hetero-aromatic and aliphatic substrates in both batch and continuous microflow (32 examples, 52-98% yield). Process intensification through continuous microflow application resulted in a 15-fold increase in production rate (0.25 mmol min-1) due to improved gas-liquid mass transfer, enhanced irradiation as well as convenient handling of the gaseous CF3 source. Furthermore, the efficiency of the flow process allowed to reduce the amount of CF3I (1.1 equivalent) to reach full conversion. This journal is
- Straathof, Natan J. W.,Tegelbeckers, Bart J. P.,Hessel, Volker,Wang, Xiao,Nol, Timothy
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p. 4768 - 4773
(2015/01/09)
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- Copper-mediated oxidative trifluoromethylthiolation of aryl boronic acids with CF3CO2Na and elemental sulfur
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A practical three-component copper-mediated oxidative trifluoromethylthiolation of aryl boronic acids with cheap and readily available sodium trifluoroacetate and elemental sulfur is reported. A variety of trifluoromethylthio-substituted aromatics are synthesized in moderate yields under mild reaction conditions.
- Zhai, Lijuan,Li, Yaming,Yin, Jun,Jin, Kun,Zhang, Rong,Fu, Xinmei,Duan, Chunying
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p. 10262 - 10266
(2013/11/19)
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- A sterically demanding organo-superbase avoids decomposition of a naked trifluoromethyl carbanion directly generated from fluoroform
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A simple strategy avoiding the decomposition of a naked trifluoromethyl anion to difluorocarbene by a sterically very demanding organo-superbase without the help of a trifluoromethyl anion reservoir such as DMF is reported. The direct non-metallic trifluoromethylation of carbonyl compounds using fluoroform in the presence of t-Bu-P4 base afforded trifluoromethyl alcohols in high yields.
- Kawai, Hiroyuki,Yuan, Zhe,Tokunaga, Etsuko,Shibata, Norio
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supporting information
p. 1446 - 1450
(2013/05/09)
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- Convenient synthesis and isolation of trifluoromethylthio-substituted building blocks
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Various aryl-, heteroaryl-, and alkyl mercaptanes (RSH, 1a-r) were treated with a slight excess of NaH suspended in DMF to make the appropriate sodium thiolates (RSNa), which then reacted with 1.3 equivalent of CF3I at room temperature for overnight to afford the appropriate trifluoromethyl sulfides (CF3SR, 2) in fair to good yields. The radical chain alkylation reaction was effective without the use of UV irradiation with all but three substrates (thiosalicylic acid, 1k; 2-mercaptobenzimidazole, 1q; and 3-mercaptopropionic acid, 1r). Steam-distillation was found as an effective and easy to upscale means for the isolation of these volatile and water immiscible sulfides. The CF3I reagent gas was conveniently weighed and delivered to the reaction mixture by the balloon technique or as a preliminary made stock solution in DMF or DMSO. The sulfides 2 obtained here were assayed by GC and characterized by 1H, 13C, 19F NMR and MS spectroscopy.
- Harsányi, Antal,Dorkó, éva,Csapó, ágnes,Bakó, Tibor,Peltz, Csaba,Rábai, József
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experimental part
p. 1241 - 1246
(2011/11/12)
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- Selective oxidation and chlorination of trifluoromethylsulfide using trichloroisocyanuric acid in ionic liquid
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A route to chemoselective oxidation and chlorination of aryltrifluoromethylsulfide using trichloroisocyanuric acid (TCCA) in ionic liquid, an efficiently O-methylation reaction and a reduction of nitro- to amido- in excellent yields have been developed.
- Tang, Ri-Yuan,Zhong, Ping,Lin, Qiu-Lian
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p. 636 - 640
(2008/01/06)
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- Trifluoromethanesulfinic acid derivatives as nucleophilic trifluoromethylating reagents
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Secondary trifluoromethanesulfinamides and alkyl trifluoromethanesulfinates can be used as nucleophilic trifluoromethylating reagents towards various electrophiles by action of potassium tert-butoxide.
- Inschauspe, David,Sortais, Jean-Baptiste,Billard, Thierry,Langlois, Bernard R.
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p. 233 - 235
(2007/10/03)
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- Synthetic Uses of Thio- and Selenoesters of Trifluoromethylated Acids. 1. Preparation of Trifluoromethyl Sulfides and Selenides
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Trifluorothioacetates (CF3CO-S-R, from (CF3CO)2O and thiols) as well as trifluoromethanethio-or trifluoromethaneselenosulfonates (CF3SO2-Y-R; Y = S, Se; from CF3SO2Na, RYYR, and Br2) can be formally decarbonylated or desulfonylated, respectively, provided that they are photolyzed at 40°C in the presence of 1 equiv of the corresponding disulfide or diselenide. Trifluoromethyl sulfides or selenides are obtained, and the added disulfide (or diselenide) is recovered after reaction. In such a way, S-(trifluoromethyl)cysteine derivatives can be obtained.
- Billard, Thierry,Roques, Nicolas,Langlois, Bernard R.
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p. 3813 - 3820
(2007/10/03)
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- A convenient synthesis of trifluoromethyl aryl sulfides
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Trifluoromethyl aryl sulfides are obtained in moderate/good yields by heating potassium trifluoroacetate and aryl disulfides in sulfolane. Copyright (C) 1996 Elsevier Science Ltd.
- Quiclet-Sire, Beatrice,Saicic, Radomir N.,Zard, Samir Z.
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p. 9057 - 9058
(2007/10/03)
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- Electrochemical initiation by sulfur dioxide of radical-chain trifluoromethylation processes of thiophenols with bromotrifluoromethane
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Sulfur dioxide may serve as an efficient catalyst for the electrochemical trifluoromethylation of thiophenols by Freon F13B1 (CF3Br), which enables implementation of trifluoromethylation in an energy-saving radical-chain regime. - Keywords: Electrochemical trifluoromethylation; Thiophenols; Radical-chain processes; Bromotrifluoromethane; Sulfur dioxide catalyst
- Koshechko, V. G.,Kiprianova, L. A.,Fileleeva, L. I.,Rozhkova, Z. Z.
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p. 277 - 278
(2007/10/02)
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- Nucleophilic trifluoromethylation of organic substrates using (trifluoromethyl)trimethylsilane in the presence of a fluoride anion. II. A convenient route to aryltrifluoromethyl-sulfides, - sulfoxides and -sulfones
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Aryltrifluoromethyl-sulfides, -sulfoxides and -sulfones can be prepared by trifluoromethylation of the corresponding arylsulfenyl, -sulfinyl and -sulfonyl halides using (trifluoromethyl)trimethylsilane in the presence of fluoride sources, such as TASF . - Keywords: Nucleophilic trifluoromethylation; (Trifluoromethyl)trimethylsilane; Fluoride anion; Aryltrifluoromethylsulfides; Aryltrifluoromethylsulfoxides; Aryltrifluoromethylsulfones
- Movchun, Valeria N.,Kolomeitsev, Alexander A.,Yagupolskii, Yurii L.
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p. 255 - 258
(2007/10/02)
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- TRIFLUOROMETHYLATION OF AROMATIC AMINO AND THIO COMPOUNDS BY BISTRIFLUOROMETHYL TELLURIDE
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The reaction of aromatic and heterocyclic amines with (CF3)2Te gave the products from trifluoromethylation in the aromatic ring.The reaction with the corresponding thiols gave S-trifluoromethyl derivatives.
- Naumann, D.,Pazenok, S. V.,Turra, V.
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p. 128 - 130
(2007/10/02)
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- Direct Trifluoromethylthiolation of Aryl Halides using Methyl Fluorosulfonyldifluoroacetate and Sulfur
-
In the presence of S8 and copper(I) iodide, methyl fluorosulfonyldifluoroacetate 1 reacts with aryl halides 2 in hexamethylphosphoramide (HMPA) or N-methylpyrrolidinone (NMP) at 100-110 deg C to give the corresponding trifluoromethylthiolated derivatives 3 in good yields.
- Chen, Qing-Yun,Duan, Jian-Xing
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p. 918 - 919
(2007/10/02)
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- A new convenient method for the synthesis of perfluoroalkylarylsulfides
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Methylviologen has been shown to be an effective homogeneous catalyst in the perfluoroalkylation of thiophenols with perfluoroalkyliodides.
- Koshechko,Kiprianova,Fileleeva
-
p. 6677 - 6678
(2007/10/02)
-
- ELECTROCHEMICAL INITIATION OF THE RADICAL-ION REACTIONS OF PERFLUOROALKYL HALIDES II. ELECTROCHEMICAL SYNTHESIS OF ARYL AND ALKYL POLYFLUOROALKYL SULFIDES
-
An electrochemical method was developed for the synthesis of aryl and alkyl polyfluoroalkyl sulfides based on the electrochemical initiation of the radical-ion chain reaction of thiolate ions with perfluoro- and polyfluoroalkyl iodides and bromides.
- Ignat'ev, N. V.,Datsenko, S. D.,Yagupol'skii, L. M.
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p. 780 - 784
(2007/10/02)
-
- TRIFLUOROMETHYLATION OF ORGANIC DISULFIDES WITH SODIUM TRIFLUOROMETHANESULFINATE UNDER OXIDATIVE CONDITIONS: SYNTHESIS OF TRIFLUOROMETHYL THIOETHERS.
-
Trifluoromethyl thioethers can be obtained from disulfides, sodium trifluoromethanesulfinate and an oxidizer like t-BuOOH, CAN or K2S2O8.The reaction seems to be a radical one and one half of the disulfide molecule only is used for trifluoromethylation.Yields are related to the nucleophilicity of the sulfur atoms.The choice of the solvent can be crucial, especially with aromatic disulfides for which sulfur trifluoromethylation competes with nucleus one.
- Clavel, Jean-Louis,Langlois, Bernard,Laurent, Eliane,Roidot, Nathalie
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p. 169 - 172
(2007/10/02)
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- Chemistry of Halogenoperfluoroalkanes> Synthesis of Fluorinated Ethers and Thioethers via Radical or Anionic Intermediates
-
Condensation of bromotrifluoromethane with potassium thiophenoxides in DMF is performed under pressure (2-3 atm) in a glass apparatus.Inhibition by nitrobenzene shows that a SRN1 mechanism is involved in the formation of aryl trifluoromethyl sulfides.Dichlorodifluoromethane itself reacts through a similar process to give aryl chlorodifluoromethyl sulfides.Condensation of 1,1,2-trichlorotrifluoroethane with potassium thiophenoxide or phenoxide occurs even in the presence of nitrobenzene.The formation of aryl 2,2-dichloro-1,1,2-trifluoroethyl sulfides or ethers can be explained by a chain carbanionic mechanism.
- Wakselman, Claude,Tordeux, Marc
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p. 4047 - 4051
(2007/10/02)
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- Stereoelectronic and Conformational Effects in Meisenheimer Complexes. Intrinsic Reactivities of Spiro vs. 1,1-Dimethoxy and 1-Methoxy-1-phenoxy Complexes
-
Rate and equilibrium constants of formation of spiro Meisenheimer complexes derived from 1-(2-hydroxyethoxy)-2,6-dinitro-4-X-benzenes in aqueous solution are compared with those for 1,1-dimethoxy Meisenheimer complexes derived from 2,4-dinitro-4-X-anisoles.Hammett ρ values for the equilibrium constants are 8.2 for the dimethoxy and 5.9 for the spiro complexes, while the normalized ρ values for the rate constants of complex formation (cleavage) are 0.44 (-0.56) for the dimethoxy and 0.58 (-0.42) for the spiro complexes.The large difference in the equilibrium ρ values is attributed to a conformation of a dimethoxy complexes in which there is repulsion between the lone pairs on the ketal and the o-nitro group oxygens.A procedure for making the reactions in the two families thermodynamically comparable by correcting the rate and equilibrium constants for the pKa difference in the nucleophile and for intramolecularity of spiro complex formation was applied.The corrected parameters show that the spiro complexes form and decompose much faster than the dimethoxy complexes.This enhanced reactivity, ΔΔG, is attributed to a stereoelectronic effect or p-? overlap between a lone pair orbital of the nonreacting oxygen and the benzene ring, which is only feasible in the transition state of the spiro complex reaction (14) but not in the thransition state of the dimethoxy complex reaction (15).This interpretation is strongly supported by the fact that ΔΔG increases with increasing electron-withdrawing strength of X substituent.The enhanced rate of formation and decomposition of the spiro complex from catehol 2,4,6-trinitrophenyl ether compared to that of the corresponding 1-methoxy-1-phenoxy complex can be explained in a similar way.
- Bernasconi, Claude F.,Howard, Keith A.
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p. 7248 - 7257
(2007/10/02)
-
- Phase-Transfer Catalysed Ion-Radical Perfluoroalkylation of Thiols
-
It has been shown that under conditions of phase-transfer catalysis under UV-irradiation perfluoroalkyl iodides react with aliphatic and aromatic thiols in the water-organic solvent media to form alkyl or aryl perfluoroalkyl sulfides in 60-80 percent yields.
- Popov, V. I.,Boiko, V. N.,Yagupolskii, L. M.
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p. 365 - 370
(2007/10/02)
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- Process for preparing aryl trifluoromethylsulfides
-
Trifluoromethylthiocopper, formed in situ by the reaction of bis-(trifluoromethylthio)mercury with copper, reacts with aromatic bromides and iodides to give aryl trifluoromethyl sulfides.
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