- Oxidatively Induced Aryl-CF3 Coupling at Diphosphine Nickel Complexes
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This communication describes the synthesis of a series of diphosphine NiII(Ph)(CF3) complexes and studies of their reactivity toward oxidatively induced Ph-CF3 bond-forming reductive elimination. Treatment of these complexes with the one-electron outer-sphere oxidant ferrocenium hexafluorophosphate (FcPF6) affords benzotrifluoride, but the yield varies dramatically as a function of diphosphine ligand. Diphosphines with bite angles of less than 92° afforded 3. In contrast, those with bite angles between 95 and 102° formed PhCF3 in yields ranging from 62 to 77%.
- Bour, James R.,Roy, Pronay,Canty, Allan J.,Kampf, Jeff W.,Sanford, Melanie S.
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- The selective electrochemical fluorination of S-alkyl benzothioate and its derivatives
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We herein report that the regioselective anodic fluorination of S-alkyl benzothioate and its derivatives in various aprotic solvents using Et3N·nHF (n = 3-5) and Et4NF·nHF (n = 3-5) as supporting electrolyte and a fluorine source successfully provided the corresponding α-fluorinated products in moderate yields. Dichloromethane containing Et4NF·4HF was found to be the most suitable combination as electrolytic solvent and supporting salt as well as fluorine source for the anodic fluorination. The electrochemical fluorination of cyclic benzothioates such as benzothiophenone was also achieved.
- Kuribayashi, Shunsuke,Kurioka, Tomoyuki,Inagi, Shinsuke,Lu, Ho-Jung,Uang, Biing-Jiun,Fuchigami, Toshio
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- The Relationship between 19F Substituent Chemical Shifts and Electron Densities: meta- and para-Substituted Benzoyl Fluorides
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The 19F substituent chemical shifts (SCS) of meta- and para-benzoyl fluorides are found to correlate well with substituent parameters using the dual substituent parameter (DSP) equation, indicating that they reflect electronic perturbations induced by the substituent.The direction of the SCS values is such that donating substituents cause upfield shifts whilst acceptors cause downfield shifts.STO-3G calculations indicate that substituents induce only very small changes in ?-electron density about the fluorine atom, but that these changes correlate reasonably well with the observed SCS values.For the para series, the slope of the relationship between Δq?F and 19F SCS is 5000 ppm/electron, indicating the great sensitivity of the fluorine atom to small changes in electron density.
- Brownlee, Robert T. C.,Craik, David J.
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- Acyl fluorides from carboxylic acids, aldehydes, or alcohols under oxidative fluorination
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We describe a novel reagent system to obtain acyl fluorides directly from three different functional group precursors: carboxylic acids, aldehydes, or alcohols. The transformation is achieved via a combination of trichloroisocyanuric acid and cesium fluoride, which facilitates the synthesis of various acyl fluorides in high yield (up to 99%). It can be applied to the late-stage functionalization of natural products and drug molecules that contain a carboxylic acid, an aldehyde, or an alcohol group.
- Liang, Yumeng,Zhao, Zhengyu,Taya, Akihito,Shibata, Norio
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supporting information
p. 847 - 852
(2021/02/06)
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- Benzoyl Fluorides as Fluorination Reagents: Reconstruction of Acyl Fluorides via Reversible Acyl C-F Bond Cleavage/Formation in Palladium Catalysis
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This report describes the formation of value-added acyl fluorides by means of palladium-catalyzed acyl-exchange reactions between acyl fluorides and acid anhydrides. This method allows using a simple and commercially available acyl fluoride, benzoyl fluoride, as the fluoride source for the easy and efficient preparation of a variety of more complex acyl fluorides. The results of this study suggest that this reaction proceeds via a reversible acyl C-F bond cleavage/formation at the palladium center.
- Ogiwara, Yohei,Hosaka, Shintaro,Sakai, Norio
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p. 856 - 861
(2020/03/05)
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- Methoxylation of Acyl Fluorides with Tris(2,4,6-trimethoxyphenyl)phosphine via C-OMe Bond Cleavage under Metal-Free Conditions
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Acyl fluorides are subjected to methoxylation with tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) to afford the corresponding methyl esters in good to excellent yields. This transformation is featured by C(sp2)-OMe bond cleavage under metal-free conditions. Unprecedented utilization of TMPP as a methoxylating agent realized the installation of an OMe group into the desired products.
- Ishida, Takumi,Nishihara, Yasushi,Wang, Xiu,Wang, Zhenhua
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p. 7526 - 7533
(2020/06/27)
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- Cooperative NHC and Photoredox Catalysis for the Synthesis of β-Trifluoromethylated Alkyl Aryl Ketones
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Despite the great potential of radical chemistry in organic synthesis, N-heterocyclic carbene (NHC)-catalyzed reactions involving radical intermediates are not well explored. This communication reports the three-component coupling of aroyl fluorides, styrenes and the Langlois reagent (CF3SO2Na) to give various β-trifluoromethylated alkyl aryl ketones with good functional group tolerance in moderate to high yields by cooperative photoredox/NHC catalysis. The alkene acyltrifluoromethylation proceeds via radical/radical cross coupling of ketyl radicals with benzylic C-radicals. The ketyl radicals are generated via SET reduction of in situ formed acylazolium ions whereas the benzylic radicals derive from trifluoromethyl radical addition onto styrenes.
- D?ben, Nadine,Meng, Qing-Yuan,Studer, Armido
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supporting information
p. 19956 - 19960
(2020/09/04)
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- Rapid synthesis of acyl fluorides from carboxylic acids with Cu(O2CCF2SO2F)2
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Acyl fluorides have moderate electrophilicity and a very good balance between stability and reactivity. Utilization of acyl fluorides as versatile building blocks in transition-metal catalysis attracts fast-growing and great attention recently. Development of rapid and operationally simple synthetic methods for acyl fluorides has always been desirable. We report herein a rapid, simple and efficient acyl fluoride synthesis from carboxylic acids with Cu(O2CCF2SO2F)2 as a deoxofluorination reagent. Notably, Cu(O2CCF2SO2F)2 was readily prepared in large scale from inexpensive starting material, and previously used as a good trifluoromethylating reagent.
- Le, Bingjun,Wu, Hao,Hu, Xiaojun,Zhou, Xiumiao,Guo, Yong,Chen, Qing-Yun,Liu, Chao
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supporting information
(2020/11/20)
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- Nickel-catalyzed decarbonylative stannylation of acyl fluorides under ligand-free conditions
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Nickel-catalyzed decarbonylative stannylation of acyl fluorides under ligand-free conditions was disclosed. A variety of aromatic acyl fluorides are capable of reacting with silylstannanes in the presence of cesium fluoride. A one-pot decarbonylative stannylation/Migita-Kosugi-Stille reaction of benzoyl fluoride, giving rise to the direct formation of the corresponding cross-coupled products, further demonstrated the synthetic utility of the present method. This newly developed methodology with a good functional-group compatibility via C-F bond cleavage and C-Sn bond formation under nickel catalysis opens a new area for the functionalization of acyl fluorides in terms of carbon-heteroatom bond formation.
- Wang, Xiu,Wang, Zhenhua,Liu, Li,Asanuma, Yuya,Nishihara, Yasushi
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- High-throughput evaluation of in situ-generated cobalt(III) catalysts for acyl fluoride synthesis
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Using a high-throughput experimental procedure, a series of cobalt(iii) complexes of the general formula CpRCo(I)(X)(L) were prepared and screened for their activity towards the catalytic nucleophilic fluorination of benzoyl chloride. A highly active catalyst was identified, and successfully employed in a mild and effective protocol for the synthesis of a group of acyl fluoride compounds.
- Lee, Graham M.,Clément, Roxanne,Baker, R. Tom
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p. 4996 - 5003
(2017/11/09)
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- Sulfur–Fluoride Exchange (SuFEx)-Mediated Synthesis of Sterically Hindered and Electron-Deficient Secondary and Tertiary Amides via Acyl Fluoride Intermediates
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Amide bond formation is one of the most executed reactions in chemistry and biology. This is largely due to the ubiquity of the amide functional group in biological molecules, natural products and pharmaceutically important drugs. We report here the development of “SuFExAmide”: a new sulfur–fluoride exchange (SuFEx) click chemistry based protocol for the efficient amidation of carboxylic acids via acyl fluoride intermediates. We have developed benzene-1,3-disulfonyl fluoride as a cost effective, powerful and versatile coupling agent, which delivers challenging secondary and tertiary amides in excellent yields from sterically hindered and electron-deficient amines. The straightforward method offers significant benefits over existing protocols in terms of substrate scope, efficiency and ease of operation and is demonstrated by the synthesis of 44 amides, including GNF6702, an antiprotozoal drug candidate. In the majority of cases, the amide products are obtained in high yield without the need for excess reagents or chromatographic purification.
- Smedley, Christopher J.,Barrow, Andrew S.,Spiteri, Christian,Giel, Marie-Claire,Sharma, Pallavi,Moses, John E.
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supporting information
p. 9990 - 9995
(2017/08/01)
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- Enantioselective acylation of silyl ketene acetals through fluoride anion-binding catalysis
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A highly enantioselective acylation of silyl ketene acetals with acyl fluorides has been developed to generate useful α,α-disubstituted butyrolactone products. This transformation is promoted by a new thiourea catalyst and 4-pyrrolidinopyridine and represents the first example of enantioselective thiourea anion-binding catalysis with fluoride.
- Birrell, James A.,Desrosiers, Jean-Nicolas,Jacobsen, Eric N.
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supporting information; experimental part
p. 13872 - 13875
(2011/10/09)
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- Reactions of alcohols with cesium fluoroxysulfate
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The reactions of alcohols with cesium fluoroxysulfate (CsSO4F) in MeCN suspension were studied, and the role of the structure of the alcohol and the reaction conditions on the course of reaction was determined. Secondary benzyl alcohols bearing a nonactivating aromatic ring were selectively oxidized to the corresponding ketones, while the CsSO4F-mediated reaction of phenyl-1-naphthylmethanol resulted in the formation of 1-fluoronaphthalene and benzaldehyde. Cyclic and noncyclic secondary alcohols were readily converted to ketones, as well as 1-hydroxybenzecyclanes to benzocyclanones- 1, without any further fluorination or oxidation under the reaction conditions. On the other hand, reactions of primary alcohols with CsSO4F resulted in the formation of acid fluorides derived from further fluorination of aldehydes. Another type of transformation was observed in the case of alcohols bearing a benzyl functional group attached geminal to a hydroxy group, where decarbanylation of reactive intermediates resulting in the formation of benzyl fluoride derivatives became the main process. 2- Phenylethanol was so converted to benzyl fluoride and phenylacetyl fluoride in a 3:1 relative ratio, while 2-phenyl-1-propanol was selectively transformed to 1-phenyl-1-fluoroethane. The presence of the radical inhibitor nitrobenzene in the reaction mixture considerably inhibited conversion of the starting material. The same effect was observed by lowering the solvent polarity. Hammett correlation analysis of the effect of substituents on the reaction rates of oxidation of a set of substituted 1-phenyl-1-ethanols to acetophenones gave the reaction constant p+ = -0.32, while analysis of analogous data for the transformations of benzyl alcohols to benzoyl fluorides gave the value of -0.54. A mechanism including radical intermediates was proposed for the transformation of alcohols by CsSO4F.
- Stavber, Stojan,Kosir, Iztok,Zupan, Marko
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p. 4916 - 4920
(2007/10/03)
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- Reactions of Aldehydes with Cesium Fluoroxysulfate
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Various aromatic and aliphatic aldehydes reacted at 35-40 deg C in CH3CN with CsSo4F giving acid fluorides in a good yield.In some cases formation of fluorohydrocarbons was also observed.Hammett correlation analysis of the transformation of various substituted benzaldehydes (p-OCH3, p-CH3, p-F, p-CF3, m-NO2) gave the reaction constant ρ+ = -0.38.Solvent polarity strongly influenced the conversion of aldehydes into acid fluorides, being in acetonitrile almost quantitative and completely halted in CH2Cl2, n-hexane, or tetrahydrofuran.The presence of nitrobenzene, often used as a radical scavenger, considerably reduced the acid fluoride formation.Based on experimental observations was concluded that the main intermediates involved in the conversion of aldehydes into acid fluorides with CsSO4F must be of a radical nature.
- Stavber, Stojan,Planinsek, Zdenka,Zupan, Marko
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p. 5334 - 5337
(2007/10/02)
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- 'HALEX' FLUORINATION OF CHLORINATED BENZALDEHYDES AND BENZOYL CHLORIDES
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Spray-dried potassium fluoride, suspended in sulpholane at 220 degC, converted 2,4- and 2,6-dichlorobenzaldehyde into the corresponding difluoroaldehydes (yields ca. 65percent).Small amounts of the mono-substituted products (2-chloro-4-fluoro- + 4-chloro-2-fluorobenzaldehyde, and 2-chloro-6-fluoro-benzaldehyde, respectively) were also produced.Similar treatment of the 3,4-dichloro-analogue gave 3-chloro-4-fluorobenzaldehyde (yield 98percent, conversion 68percent), but 2- and 4-chlorobenzaldehyde gave very poor yields (ca. 5percent) of the 2- and 4-fluoro-derivatives. 2-Fluoro-, 4-fluoro- and 3-chloro-4-fluorobenzoyl fluoride were obtained (yields 60-65percent) by heating the corresponding chlorobenzoyl chlorides with potassium fluoride in sulpholane.
- Banks, R. Eric,Mothersdale, Kevin N.,Tipping, Anthony E.,Tsiliopoulos, Efthimios,Cozens, Barry J.,et al.
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p. 529 - 537
(2007/10/02)
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- Tetraphenylphosphonium Salts-Grafted Copolymers as Catalysts for Halogen-Exchange Fluorinations
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Cross-linked styrene/2-(4-chlorophenyl)propene copolymer-grafted tetraphenylphosphonium salt was an effective and reusable catalyst for the reaction of aromatic chlorides with anhydrous potassium fluoride to afford the corresponding aromatic fluorides in good yields.
- Yoshida, Yasuo,Kimura, Yoshikazu,Tomoi, Masao
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p. 769 - 772
(2007/10/02)
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- Preparation of fluoroaromatic compounds in dispersion of potassium fluoride
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An improved process is disclosed for preparing fluoroaromatic compounds (such as fluoronitrobenzene compounds) wherein chloroaromatic compounds (such as chloronitrobenzene compounds) are reacted with potassium fluoride in a solvent dispersion thereof prepared from a mixture including the solvent, the fluoride, methanol and an aromatic compound.
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