- Monofluoromethylation of tetrahydroisoquinolines by visible-light induced direct C(sp3)-H bond activation
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A visible-light photoredox-catalyzed reaction of tetrahydroisoquinolines with β-fluorinated gem-diols results in the formation of C1-monofluoromethylated tetrahydroisoquinolines via C(sp3)-H bond activation. This protocol provides a new method to introduce a CF group with stable, easily-prepared monofluorinated gem-diol as CF source. A mechanistic investigation is presented based on control experiments.
- Li, Weipeng,Zhu, Yunhuang,Duan, Yingqian,Zhang, Muliang,Zhu, Chengjian
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Read Online
- Synthesis method of alpha or beta-substituted aromatic ketone
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The invention discloses a synthesis method of alpha-or beta-substituted aromatic ketone. The method comprises the following steps: under the condition of inert gas, reacting alpha-oxo-aryl ethanone compounds, B2pin2, PDI-CoCl2 and MBHEt3 in an organic solvent at room temperature, then adding a compound 2, and continuously reacting to obtain a compound 3, wherein in the MBHEt3, M is an alkali metal; the compound 2 is selected from the group consisting of deuterated methanol, Selectfluoro, a TogniII reagent or R2CHO; R2 is an aromatic substituent or alkyl; the organic solvent is an aprotic organic solvent. According to the method, the alpha-oxo aryl ethanone is used as a raw material, a cheap and stable boron reagent and an efficient cobalt catalyst which is cheap and easy to obtain are used, an activating reagent MBHEt3 is added to generate an enol boron ether intermediate, then the enol boron ether intermediate and different electrophilic reagents are synthesized into alpha-or beta-substituted aromatic ketone, the reaction is carried out at normal temperature, and the operation is convenient.
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Paragraph 0022-0027; 0081-0085
(2021/05/01)
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- Direct Trifluoromethoxylation without OCF3-Carrier through In Situ Generation of Fluorophosgene
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Owing to the high interest in the OCF3 group for pharmaceutical and agrochemical applications, trifluoromethoxylation received great attention in the last years with several new methods for this approach towards OCF3-comprising compounds. Yet, it most often requires the beforehand preparation of specific F3CO? transfer reagents, which can be toxic, expensive, unstable, and/or generate undesired side-products upon consumption. To circumvent this, the in-situ generation of gaseous fluorophosgene from triphosgene, its conversion by fluoride into the OCF3 anion, and the direct use of the latter in nucleophilic substitutions is an appealing strategy, which, although recently approached, has not been fully exploited. We disclose herein our efforts towards this aim.
- Donnard, Morgan,Guérin, Thomas,Hanquet, Gilles,Leroux, Frédéric R.,Panossian, Armen,Saiter, Jérémy
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supporting information
p. 3139 - 3147
(2021/06/26)
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- Method for synthesizing alpha-fluorinated ketone through hydrazone aliphatic chain monoketone
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The invention belongs to the technical field of organic synthesis, and provides a method for synthesizing alpha-ketone fluoride through hydrazone aliphatic chain monoketone, which comprises the following steps of: reacting aliphatic chain monoketone with hydrazine hydrate to obtain hydrazone, and reacting hydrazone with a compound represented by formula 2 under a heating condition to complete hydrazone defluorination. The fluorinated product is widely applied to medicines, the reaction conditions are mild, and the process is simple.
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Paragraph 0074-0076
(2021/02/06)
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- Unbalanced-Ion-Pair-Catalyzed Nucleophilic Fluorination Using Potassium Fluoride
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An unbalanced ion pair promoter (e.g., tetrabutylammonium sulfate), consisting of a bulky and charge-delocalized cation and a small and charge-localized anion, greatly accelerates nucleophilic fluorinations using easy handling KF. We also successfully converted an inexpensive and commercially available ion-exchange resin to the polymer-supported ion pair promoter (A26–SO42–), which could be reused after filtration. Moreover, A26–SO42– can be used in continuous flow conditions. In our conditions, water is well-tolerated.
- Hammond, Gerald B.,Li, Wangbing,Lu, Zhichao,Xu, Bo
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supporting information
p. 9640 - 9644
(2021/12/14)
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- Steric-Free Bioorthogonal Labeling of Acetylation Substrates Based on a Fluorine-Thiol Displacement Reaction
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We have developed a novel bioorthogonal reaction that can selectively displace fluorine substitutions alpha to amide bonds. This fluorine-thiol displacement reaction (FTDR) allows for fluorinated cofactors or precursors to be utilized as chemical reporters, hijacking acetyltransferase-mediated acetylation both in vitro and in live cells, which cannot be achieved with azide- or alkyne-based chemical reporters. The fluoroacetamide labels can be further converted to biotin or fluorophore tags using FTDR, enabling the general detection and imaging of acetyl substrates. This strategy may lead to a steric-free labeling platform for substrate proteins, expanding our chemical toolbox for functional annotation of post-translational modifications in a systematic manner.
- Lyu, Zhigang,Zhao, Yue,Buuh, Zakey Yusuf,Gorman, Nicole,Goldman, Aaron R.,Islam, Md Shafiqul,Tang, Hsin-Yao,Wang, Rongsheng E.
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supporting information
p. 1341 - 1347
(2021/02/01)
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- LINKING AMINO ACID SEQUENCES, MANUFACTURING METHOD THEREOF, AND USE THEREOF
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This invention provides compositions comprising linked amino acid sequences, pharmaceutical compositions comprising linked amino acid sequences, and methods of making thereof. This invention also provides methods of delivering said compositions to subjects and methods of treating various disorders and diseases using the said compositions.
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Page/Page column 16; 109; 126
(2021/08/20)
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- Alpha-fluorochalcone derivative and application thereof
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The invention provides an alpha-fluorochalcone derivative and application thereof. The derivative comprises pharmaceutically acceptable salt of the derivative. The invention also provides an application of the derivative and the pharmaceutically acceptable salt thereof in preparation of drugs for treating PPAR receptor related diseases. The derivative provided by the invention has the characteristics of good in-vivo absorption, high bioavailability and strong drug effect, thereby having huge clinical application value.
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Paragraph 0508-0509; 0512-0513
(2021/05/22)
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- Organo-catalyzed Michael addition of 2-fluoro-2-arylacetonitriles
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An efficient synthesis of a variety of 2-arylacetonitriles containing a fluorinated stereogenic center through organo-catalyzed Michael addition reaction of 2-fluoro-2-arylacetonitriles has been developed. This protocol uses a cheap organocatalyst (DBU) and has a broad substrate scope: α, β-unsaturated ketones, esters, nitriles and sulfones were all successfully reacted. Importantly, water proved to be a good solvent for this reaction.
- Chen, De-Yin,Song, Shuai,Chen, Ling-Yan,Ren, Xinfeng,Li, Ya
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supporting information
(2021/03/01)
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- Double Enzyme-Catalyzed One-Pot Synthesis of Enantiocomplementary Vicinal Fluoro Alcohols
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A double-enzyme-catalyzed strategy for the synthesis of enantiocomplementary vicinal fluoro alcohols through a one-pot, three-step process including lipase-catalyzed hydrolysis, spontaneous decarboxylative fluorination, and subsequent ketoreductase-catalyzed reduction was developed. With this approach, β-ketonic esters were converted to the corresponding vicinal fluoro alcohols with high isolated yields (up to 92percent) and stereoselectivities (up to 99percent). This new cascade process addresses some issues in comparison with traditional methods such as environmentally hazardous reaction conditions and low stereoselectivity outcome.
- Fan, Jiajie,Lin, Xianfu,Peng, Yongzhen,Wang, Anlin,Wu, Qi,Xu, Jian,Xu, Weihua,Yu, Huilei
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supporting information
(2020/07/24)
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- α-Fluorotricarbonyl Derivatives as Versatile Fluorinated Building Blocks: Synthesis of Fluoroacetophenone, Fluoroketo Ester and Fluoropyran-4-one Derivatives
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Fluorinated acyl-Meldrum's acid derivatives were synthesized by electrophilic fluorination of appropriate phenacyl Meldrum's acid substrates using Selectfluor. Reactions with water, ethanol, Grignard, and alkynyllithium reagents gave rise to the correspon
- Harsanyi, Antal,Lückener, Anne,Pasztor, Hedvig,Yilmaz, Zahide,Tam, Lawrence,Yufit, Dmitry S.,Sandford, Graham
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supporting information
p. 3872 - 3878
(2020/06/09)
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- Fluoro-Substituted Methyllithium Chemistry: External Quenching Method Using Flow Microreactors
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The external quenching method based on flow microreactors allows the generation and use of short-lived fluoro-substituted methyllithium reagents, such as fluoromethyllithium, fluoroiodomethyllithium, and fluoroiodostannylmethyllithium. Highly chemoselective reactions have been developed, opening new opportunities in the synthesis of fluorinated molecules using fluorinated organometallics.
- Colella, Marco,Degennaro, Leonardo,Higuma, Ryosuke,Ishikawa, Susumu,Luisi, Renzo,Nagaki, Aiichiro,Takahashi, Yusuke,Tota, Arianna
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p. 10924 - 10928
(2020/05/08)
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- C-F Bond Activation of a Perfluorinated Ligand Leading to Nucleophilic Fluorination of an Organic Electrophile
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We report a fluorine transfer reaction in which fluorine from a perfluorinated ligand undergoes C-F bond activation and transfers to an electrophile, resulting in the formation of a new fluorinated product and dimerization of the monodefluorinated complex. Treatment of [(η5,κ2C-C5Me4CH2C6F5CH2NC3H2NMe)-RhCl] with the organic electrophile, toluoyl chloride, resulted in the formation of a rhodium(III) metallocycle via C-F bond activation assisted defluorinative coupling. Fission of the C-F bond liberated nucleophilic fluoride, which converted acyl chloride to acyl fluoride. The overall reaction was monitored using a multivariate analysis approach in real time.
- Hanson-Heine, Magnus W. D.,Licence, Peter,Marr, Andrew C.,Morgan, Patrick J.,Saunders, Graham C.,Thomas, Hayden P.
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supporting information
p. 2116 - 2124
(2020/07/23)
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- Fluorine containing cyclopropanes: Synthesis of aryl substituted all-: cis 1,2,3-trifluorocyclopropanes, a facially polar motif
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The syntheses of substituted all-cis-1,2,3-trifluorocyclopropanes are described for the first time. The three fluorines located on each of the cyclopropyl carbons with a stereochemistry where they are all on the same face of the cyclopropane, imparts a significant polarity to the molecule, and the inherent conformational rigidity and lowering of logP makes this motif attractive for exploration as a substituent for pharmaceuticals and agrochemicals research.
- Fang, Zeguo,Cordes, David B.,Slawin, Alexandra M. Z.,O'hagan, David
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p. 10539 - 10542
(2019/09/06)
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- Exploiting a beast in carbenoid chemistry: Development of a straightforward direct nucleophilic fluoromethylation strategy
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The first direct and straightforward nucleophilic fluoromethylation of organic compounds is reported. The tactic employs a fleeting lithium fluorocarbenoid (LiCH2F) generated from commercially available fluoroiodomethane. Precise reaction conditions were developed for the generation and synthetic exploitation of such a labile species. The versatility of the strategy is showcased in ca. 50 examples involving a plethora of electrophiles. Highly valuable chemicals such as fluoroalcohols, fluoroamines, and fluoromethylated oxygenated heterocycles could be prepared in very good yields through a single synthetic operation. The scalability of the reaction and its application to complex molecular architectures (e.g., steroids) are documented.
- Parisi, Giovanna,Colella, Marco,Monticelli, Serena,Romanazzi, Giuseppe,Holzer, Wolfgang,Langer, Thierry,Degennaro, Leonardo,Pace, Vittorio,Luisi, Renzo
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supporting information
p. 13648 - 13651
(2017/11/06)
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- Decarboxylative fluorination of β-Ketoacids with N-fluorobenzenesulfonimide (NFSI) for the synthesis of α-fluoroketones: Substrate scope and mechanistic investigation
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Cesium carbonate (Cs2CO3)-mediated decarboxylative fluorination of β-ketoacids using NFSI in the MeCN/H2O mixed solvent system affords α-fluoroketones with a broad scope. Both electron-rich and electron-deficient α-non-substituted β-ketoacids are amenable to this protocol. The mechanistic study indicates that the reaction proceeds through electrophilic fluorination followed by decarboxylation, which is different from the decarboxylative fluorination of normal carboxylic acids.
- Zhang, Rui,Ni, Chuanfa,He, Zhengbiao,Hu, Jinbo
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p. 166 - 172
(2017/09/18)
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- Α - fluoro acetophenone derivative
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PROBLEM TO BE SOLVED: To provide a new production method of an α-fluoroacetophenone derivative by a simple one-step fluorination reaction with an acetophenone derivative under a mild condition.SOLUTION: An acetophenone derivative represented by formula (I) is reacted with a hydrogen fluoride/amine complex in the presence of a hypervalent iodine compound, (in the formula, a ring A indicates an aromatic ring of 1-3 members; Rindicates a hydrogen atom or an aromatic ring of 1-3 members that may be substituted; Rindicates a hydrogen atom or an alkyl group of 1-6 carbons; and Rindicates a hydrogen atom, an alkyl group of 1-6 carbons, an alkoxy group of 1-6 carbons or a halogen atom). The H part in formula (I) is substituted and fluorinated.
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Paragraph 0022; 0024-0026; 0044-0046
(2018/08/28)
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- Linking of Alcohols with Vinyl Azides
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A protocol to link alcohols with vinyl azides has been established through fluoro- or bromo-alkoxylation of vinyl azides to provide α-alkoxy-β-haloalkyl azides. A series of primary and secondary alcohols including natural products and their derivatives such as sugars and steroids were successfully anchored with vinyl azides. The as-prepared cyanine dye linked testosterones were capable of rapid cell membrane imaging in real time.
- Wang, Yi-Feng,Hu, Ming,Hayashi, Hirohito,Xing, Bengang,Chiba, Shunsuke
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p. 992 - 995
(2016/03/15)
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- Synthesis of α-Fluoroketones from Vinyl Azides and Mechanism Interrogation
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An efficient and mild fluorination of vinyl azides for the synthesis of α-fluoroketones is described. The mechanistic studies indicated that a single-electron transfer (SET) and a subsequent fluorine atom transfer process could be involved in the reaction.
- Wu, Shu-Wei,Liu, Feng
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p. 3642 - 3645
(2016/08/16)
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- Nucleophilic (Radio)Fluorination of α-Diazocarbonyl Compounds Enabled by Copper-Catalyzed H-F Insertion
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The copper-catalyzed H-F insertion into α-diazocarbonyl compounds is described using potassium fluoride (KF) and hexafluoroisopropanol. Access to complex α-fluorocarbonyl derivatives is achieved under mild conditions, and the method is readily adapted to
- Gray, Erin E.,Nielsen, Matthew K.,Choquette, Kimberly A.,Kalow, Julia A.,Graham, Thomas J. A.,Doyle, Abigail G.
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supporting information
p. 10802 - 10805
(2016/09/09)
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- Photoreductive transformation of fluorinated acetophenone derivatives on titanium dioxide: Defluorination vs. reduction of carbonyl group
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Photoreductive transformation of mono- and di-fluoromethyl acetophenone (AP) derivatives on the P25 titanium dioxide (TiO2) has been studied in deaerated ethanol solution under UV irradiation. 2-Monofluoromethyl AP (MFAP) was stable in the dark and existed as keto form in ethanol, whereas 64% of 2,2-difluoromethyl AP (DFAP) transformed into hemiketal form (photocatalytically inactive form) under the same condition. Under the UV irradiation with the TiO2 particles, the reduction of MFAP afforded only the defluorinated ketone, while the reduction of DFAP provided not only defluorinated ketones but also a hydrogenated alcohol. The reduction of carbonyl group and defluorination of DFAP concurrently occurred on TiO2, in which the formation of MFAP was observed as an intermediate of the sequential defluorinations. These two parallel reactions were initiated by electron transfer from the surface defect sites (Tisd) to DFAP adsorbed on the TiO2 surface. A possible reaction mechanism for DFAP is proposed and discussed on the basis of thermodynamic data upon the C-F bond cleavage of anion radical species generated during the photocatalysis.
- Kohtani, Shigeru,Kurokawa, Takuya,Yoshioka, Eito,Miyabe, Hideto
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- Palladium-catalyzed direct mono-α-arylation of α-fluoroketones with aryl halides or phenyl triflate
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A palladium catalyzed Negishi-type α-arylation of α-fluoroketones with electron-rich and electron-deficient aryl halides or phenyl triflate has been developed. This direct mono-α-arylation method generate a variety of ternary α-aryl-α-monofluoroketones easily in good to excellent yields using XPhos as ligand and Cs2CO3as mild base.
- Zhou, Jun,Fang, Xiang,Shao, Tongle,Yang, Xueyan,Wu, Fanhong
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supporting information
p. 54 - 62
(2016/10/05)
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- Fluorination of α-bromomethyl aryl ketones with fluorohydrogenate-based ionic liquids
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Fluorination of α-bromomethyl aryl ketones using fluorohydrogenate-based ionic liquids as fluorinating reagent is described. Reaction of various α-bromomethyl aryl ketones (1a-g) with fluorohydrogenate-based ionic liquids such as EMIMF·(HF)2.3, PYR13F·(HF)2.3 or PYR14F·(HF)2.3 as a fluoride ion source in anhydrous THF led to the formation of the corresponding α-fluoromethyl aryl ketones (2a-g) in very good yield. Compared to alternative fluorinating agents for this reaction, fluorohydrogenate-based ionic liquids are safer to handle and have the potential to be less expensive and more selective.
- Singh, Rajendra P.,Martin, Jerry L.
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- FLUORONATION OF α -HALOALKYL KETONES
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The present invention provides methods and processes for producing α-fluoroalkyl ketones from non-fluoro α-haloalkyl ketones using a fluorohydrogenate compound. In some embodiments, the fluorohydrogenate compound is an ionic liquid. One particular method of the invention utilizes a fluorohydrogenate ionic liquid compound of the formula: Q+[F?(HF)n], wherein Q+ is an onium cation and n is a number from 0 to 3.
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Paragraph 0053-0054
(2016/01/25)
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- Catalytic Promiscuity of Transaminases: Preparation of Enantioenriched β-Fluoroamines by Formal Tandem Hydrodefluorination/Deamination
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Transaminases are valuable enzymes for industrial biocatalysis and enable the preparation of optically pure amines. For these transformations they require either an amine donor (amination of ketones) or an amine acceptor (deamination of racemic amines). Herein transaminases are shown to react with aromatic β-fluoroamines, thus leading to simultaneous enantioselective dehalogenation and deamination to form the corresponding acetophenone derivatives in the absence of an amine acceptor. A series of racemic β-fluoroamines was resolved in a kinetic resolution by tandem hydrodefluorination/deamination, thus giving the corresponding amines with up to greater than 99 % ee. This protocol is the first example of exploiting the catalytic promiscuity of transaminases as a tool for novel transformations.
- Cuetos, Aníbal,García-Ramos, Marina,Fischereder, Eva-Maria,Díaz-Rodríguez, Alba,Grogan, Gideon,Gotor, Vicente,Kroutil, Wolfgang,Lavandera, Iván
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supporting information
p. 3144 - 3147
(2016/03/12)
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- Rh-Catalyzed arylation of fluorinated ketones with arylboronic acids
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The Rh-catalyzed arylation of fluorinated ketones with boronic acids is reported. This efficient process allows access to fluorinated alcohols in high yields under mild conditions. Competition experiments suggest that difluoromethyl ketones are more reactive than trifluoromethyl ketones in this process, despite their decreased electronic activation, an effect we postulate to be steric in origin.
- Dobson, Luca S.,Pattison, Graham
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supporting information
p. 11116 - 11119
(2016/09/19)
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- Synthesis of α-Fluoroketones by Insertion of HF into a Gold Carbene
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Reported is an efficient synthesis of α-fluoroketones by insertion of hydrogen fluoride (HF) into the gold carbene intermediate, generated from a cationic gold catalyzed addition of N-oxides to alkynes. This method results in excellent chemical yields for a wide range of alkyne substrates and demonstrates good functional-group tolerance.
- Zeng, Xiaojun,Liu, Shiwen,Shi, Zhenyu,Liu, Guangchang,Xu, Bo
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supporting information
p. 10032 - 10036
(2016/08/16)
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- One-Pot Synthesis of α-Fluoroketones and 3-Fluoro-2,4-diaryl-furans from Trifluoromethyl β-Diketones via Decarboxylation
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A facile and mild one-pot protocol via decarboxylation of trifluoromethyl β-diketones has been developed for the construction of α-fluoroketones and 3-fluoro-2,4-diarylfurans which are important units in many biologically active compounds and useful precursors in a variety of functional-group transformations.
- Shao, Tongle,Fang, Xiang,Yang, Xueyan
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supporting information
p. 1835 - 1840
(2015/08/06)
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- A Practical Synthesis of α-Fluoroketones in Aqueous Media by Decarboxylative Fluorination of β-Ketoacids
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A practical and novel process for the decarboxylative fluorination of β-ketoacids in water in the presence of phase transfer catalyst has been developed, affording a series of α-fluoroketones in good to excellent yields. Furthermore, a preliminary investigation for the catalytic asymmetric transformation was performed and a proposed mechanistic pathway for this catalytic process was proposed.
- Li, Jian,Li, Yin-Long,Jin, Nan,Ma, Ai-Lun,Huang, Ya-Nan,Deng, Jun
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supporting information
p. 2474 - 2478
(2015/08/18)
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- Fluoronation of alpha-haloalkyl ketones
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The present invention provides methods and processes for producing α-fluoroalkyl ketones from non-fluoro α-haloalkyl ketones using a fluorohydrogenate compound. In some embodiments, the fluorohydrogenate compound is an ionic liquid. One particular method of the invention utilizes a fluorohydrogenate ionic liquid compound of the formula: Q+[F.(HF)n], wherein Q+ is an onium cation and n is a number from 0 to 3.
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Page/Page column 9
(2015/08/03)
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- Nucleophilic fluorination using imidazolium based ionic liquid bearing tert-alcohol moiety
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An ionic liquid bearing tert-butanol moiety ([mim-tOH][OMs]) was employed as an organocatalyst in the nucleophilic fluorination of a variety of substrates containing halogen/sulfonate as a leaving group. Low reactive metal fluorides, including KF, were used as a fluoride source in the reaction. Ionic liquid [mim-tOH][OMs] has shown excellent selectivity in nucleophilic fluorination of 2-(3-bromopropyloxy)naphthalene with KF or CsF affording 2-(3-fluoropropyloxy)-naphthalene in high yields. Among the various solvents screened, the activity of alkali metal fluoride was found to be better due to the improved solubility of both the metal fluoride and [mim-tOH][OMs] in the acetonitrile media.
- Shinde, Sandip S.,Patil, Sunil N.,Ghatge, Amruta,Kumar, Pradeep
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p. 4368 - 4374
(2015/06/16)
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- Metal-free, efficient oxyfluorination of olefins for the synthesis of α-fluoroketones
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A novel oxyfluorination of olefin reactions has been developed. The reactions involve a metal-free and green catalytic system for the synthesis of α-fluoroketones which is an important building block for organic synthesis. Moreover, this reaction system exhibits great functional group tolerance.
- Yang, Qiang,Mao, Liu-Liang,Yang, Bin,Yang, Shang-Dong
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supporting information
p. 3460 - 3463
(2014/07/21)
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- Highly efficient "on water" catalyst-free nucleophilic addition reactions using difluoroenoxysilanes: Dramatic fluorine effects
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A remarkable fluorine effect on "on water" reactions is reported. The C-FaH-O interactions between suitably fluorinated nucleophiles and the hydrogen-bond network at the phase boundary of oil droplets enable the formation of a unique microstructure to facilitate on water catalyst-free reactions, which are difficult to realize using nonfluorinated substrates. Accordingly, a highly efficient on water, catalyst-free reaction of difluoroenoxysilanes with aldehydes, activated ketones, and isatylidene malononitriles was developed, thus leading to the highly efficient synthesis of a variety of α,α- difluoro-β-hydroxy ketones and quaternary oxindoles. It's on! The C-FaH-O interactions between suitably fluorinated nucleophiles and a hydrogen-bond network at the phase boundary of an oil droplet facilitate "on water" catalyst-free reactions. Accordingly, the title reaction of difluoroenoxysilanes with aldehydes, activated ketones, and isatylidene malononitriles was developed, thus leading to α,α-difluoro-β-hydroxy ketones and quaternary oxindoles.
- Yu, Jin-Sheng,Liu, Yun-Lin,Tang, Jing,Wang, Xin,Zhou, Jian
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supporting information
p. 9512 - 9516
(2014/10/15)
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- Hypervalent iodine-promoted α-fluorination of acetophenone derivatives with a triethylamine·hf complex
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The direct fluorination reaction of acetophenone using iodosylarenes and TEA·5HF was conducted under mild conditions except for use of a HF reagent. The fluorination reaction was applied to acetophenone derivatives, acetonaphthones, benzyl phenyl ketone, propiophenone, butyrophenone, 1-indanone, and phenacyl chloride, giving selectively the corresponding α-fluoroketone derivatives in good yields.
- Kitamura, Tsugio,Muta, Kensuke,Muta, Kazutaka
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p. 5842 - 5846
(2014/07/08)
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- Synthesis of α-fluoroketones and α-fluoroenones in aqueous media
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An efficient synthesis of α-fluoroketones via the nucleophilic fluorination of α-bromoketones in water with TBAF·3H2O as the fluorinating agent was developed in this paper. In addition, a simple and efficient synthesis of α-fluoroenones through the condensation of α-fluoroketones with aldehydes promoted by sodium hydroxide in water was also discovered.
- He, Yan,Zhang, Xinying,Shen, Nana,Fan, Xuesen
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- Enabling nucleophilic substitution reactions of activated alkyl fluorides through hydrogen bonding
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It was discovered that the presence of water as a cosolvent enables the reaction of activated alkyl fluorides for bimolecular nucleophilic substitution reactions. DFT calculations show that activation proceeds through stabilization of the transition structure by a stronger F···H 2O interaction and diminishing C-F bond elongation, and not simple transition state electrostatic stabilization. Overall, the findings put forward a distinct strategy for C-F bond activation through H-bonding.
- Champagne, Pier Alexandre,Pomarole, Julien,Therien, Marie-Eve,Benhassine, Yasmine,Beaulieu, Samuel,Legault, Claude Y.,Paquin, Jean-Francois
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supporting information
p. 2210 - 2213
(2013/06/26)
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- Tandem reaction of 1,2-allenic ketone with α-halo ketone or α-halo ester in water: An efficient and sustainable synthesis of 1,3,4′-tricarbonyl compounds
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An efficient and sustainable synthesis of the otherwise difficult to obtain 1,3,4′-tricarbonyl compounds through a water mediated, TBAF·3H2O promoted unprecedented tandem reaction of 1,2-allenic ketone with α-halo ketone or α-halo ester has been developed. Remarkably enhanced reactivity and improved chemoselectivity by using water as the reaction medium was observed. The 1,3,4′-tricarbonyl compounds facilitate further versatile transformations, which underscores the importance of these products as synthetic intermediates. The Royal Society of Chemistry.
- Fan, Xuesen,He, Yan,Cui, Liangyan,Zhang, Xinying,Wang, Jianji
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supporting information; experimental part
p. 3218 - 3223
(2011/12/16)
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- Fluoro-substituted ketones from nitriles using acidic and basic reaction conditions
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Fluoro-substituted aliphatic nitriles are shown to undergo the Houben-Hoesch reactions with arenes in CF3SO3H to give fluoro-substituted ketones in good yields. The fluorine substituents appear to enhance the reactivities of the nitriles (and the nitrilium ion intermediates) compared to similar aliphatic nitriles. Fluoro-substituted ketones are also shown to be accessible through the reactions of organometallic reagents and fluoro-substituted nitriles.
- Raja, Erum K.,Klumpp, Douglas A.
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supporting information; experimental part
p. 5170 - 5172
(2011/10/13)
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- Gold-catalyzed synthesis of α-fluoro acetals and α-fluoro ketones from alkynes
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A new method to synthesize α-fluoro acetals and α-fluoro ketones is presented here. In the presence of alcohols and Selectfluor, catalytic amounts of gold selectively transformed alkynes into the corresponding fluorinated acetals or ketones depending on the reaction conditions. This protocol has been applied to both terminal and internal alkynes showing a high degree of chemo- and regioselectivity. The reaction mechanism seems to proceed via two co-existing pathways, since at least partially, the formation of the C(sp3)-F bond in the final products occurs at the metal center.
- De Haro, Teresa,Nevado, Cristina
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supporting information; body text
p. 2767 - 2772
(2010/12/25)
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- One-pot α-nucleophilic fluorination of acetophenones in a deep eutectic solvent
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Two methods of nucleophilic fluorination to prepare α-fluoroacetophenones from α-bromoacetophenones by using KF with PEG-400 or TBAF with ZnF2 are described. On the fundamental of nucleophilic fluorination, a novel method of one-pot fluorination to prepare α-fluoroacetophenones directly from acetophenones in DES was developed.
- Chen, Zizhan,Zhu, Wei,Zheng, Zubiao,Zou, Xinzhuo
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experimental part
p. 340 - 344
(2010/06/11)
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- Ruthenium-catalysed asymmetric transfer hydrogenation of para-substituted α-fluoroacetophenones
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The first examples of asymmetric transfer hydrogenation of α-fluoroacetophenones are reported. Eight para-substituted α-fluoroacetophenones have been reduced using four catalytic systems constructed of [RuCl2(p-cymene)2]2 or [RuCl2(mesitylene)2]2 in combinations with each of the ligands (1R,2R)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine ((R,R)-TsDPEN) and (1R,2R)-N-(p-toluenesulfonyl)-1,2-cyclohexanediamine ((R,R)-TsCYDN). All reactions were performed in both water and formic acid/triethylamine. The highest enantioselectivity was obtained using the (R,R)-TsDPEN ligand in a formic acid/triethylamine mixture, giving the (S)-1-aryl-2-fluoroethanols in high to moderate enantiomeric excess (97.5-84.5%). For this solvent system the presence of electron withdrawing groups in the para position reduced the enantioselectivity. Reactions performed in water generally gave lower enantioselectivity and reaction rate, although RuCl(mesitylene)-(R,R)-TsDPEN yielded the product alcohols with enantiomeric excess in the range of 95.5-76.5%.
- Fuglseth, Erik,Sundby, Eirik,Hoff, B?rd H.
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experimental part
p. 600 - 603
(2009/11/30)
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- Microwave assisted fluorination: an improved method for side chain fluorination of substituted 1-arylethanones
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A two-step, one-pot microwave (MW) assisted fluorination of 1-arylethanones to their corresponding 1-aryl-2-fluoroethanones has been developed. The first step utilises Selectfluor as a fluorinating agent in methanol forming 1-aryl-2-fluoroethanones and their corresponding dimethyl acetals. In the second step, water is added and Selectfluor acts as a Lewis acid in the hydrolytic cleavage of the dimethyl acetals. Compared to the thermal synthesis, the MW assisted method leads to a reduction in reaction time both in the fluorination and for the dimethyl acetal cleavage. Moreover, the one-pot procedure reduces reagent and solvent consumption. The method is best suited for the preparation of 1-aryl-2-fluoroethanones containing substituents that deactivates electrophilic aromatic substitution, however highly electron deficient ketones such as 1-(3,5-dinitrophenyl)ethanone reacts more slowly. Reactions using electron rich aromatic ketones had a low regioselectivity, and also produced fluoroaromatic products.
- Krane Thvedt, Thor H?kon,Fuglseth, Erik,Sundby, Eirik,Hoff, B?rd Helge
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experimental part
p. 9550 - 9556
(2010/02/27)
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- Micellar-system-mediated direct fluorination of ketones in water
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A micellar system was developed and applied for direct regioselective fluorination of a variety of cyclic and acyclic ketones to α-fluoroketones in water as reaction medium with Selectfluor F-TEDA-BF4 as fluorinating reagent. The inexpensive ionic amphiphile sodium dodecyl sulfate (SDS) was found to be an excellent promoter for fluorofunctionalization of hydrophobic ketones without prior activation or use of acid catalysts. Georg Thieme Verlag Stuttgart.
- Stavber, Gaj,Zupan, Marko,Stavber, Stojan
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scheme or table
p. 589 - 594
(2009/07/09)
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- Electrophilic and nucleophilic side chain fluorination of para-substituted acetophenones
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para-Substituted α-fluoroacetophenones have been synthesised by three different routes. Electrophilic fluorination of trimethylsilyl enol ethers of acetophenones using Selectfluor (F-TEDA-BF4, 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis-(tetrafluoroborate)) gave high to moderate yield depending on the electronic properties of the substituents. F-TEDA-BF4 mediated fluorination of acetophenones in methanol resulted in a mixture of α-fluoroacetophenones and the corresponding 2-fluoro-1,1-dimethyl acetals. The dimethyl acetals were hydrolysed using trifluoroacetic acid in water to maximise the yield of the product. Nucleophilic fluorination of α-bromoacetophenones using tetrabutylammonium hydrogen bifluoride (TBABF) led to moderate yield when having electron-donating substituents, whereas low yields were experienced when more electron-withdrawing substituents were introduced.
- Fuglseth, Erik,Thvedt, Thor H?kon Krane,M?ll, Maria F?rde,Hoff, B?rd Helge
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p. 7318 - 7323
(2008/12/21)
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- Nucleophilic fluorination of triflates by tetrabutylammonium bifluoride
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(Chemical Equation Presented) Careful examination of nucleophilicity, basicity, and leaving group ability led us to discover the nucleophilic fluorination of triflates by weakly basic tetrabutylammonium bifluoride, which provides excellent yields with minimal formation of elimination-derived side products. Primary hydroxyl groups as well as secondary hydroxyl groups in acyclic chains or in five-membered rings are excellent substrates, whereas benzylic and aldol-type secondary hydroxyl groups give poor yields as a result of the instability of their triflates.
- Kim, Kyu-Young,Bong, Chan Kim,Hee, Bong Lee,Shin, Hyunik
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p. 8106 - 8108
(2008/12/22)
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- New synthetic routes towards various α-fluorinated aryl ketones and their enantioselective reductions using baker's yeast
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Highly electrophilic dichlorofluoromethyl aryl ketones were obtained by oxidation of dichlorofluoromethyl aryl alcohols. Subsequent dechlorination of these ketones using sodium formaldehyde sulfoxylate (Rongalite) and reductive dehalogenating system SnCl2/Al led to various fluoromethyl aryl ketones and chlorofluoromethyl aryl ketones, respectively. Asymmetric reductions of these fluorinated ketones using the inexpensive baker's yeast produced the corresponding fluoromethyl aryl alcohols with different enantioselectivities.
- Barkakaty, Balaka,Takaguchi, Yutaka,Tsuboi, Sadao
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p. 970 - 976
(2007/10/03)
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- Effect of fluorine on palladium-catalyzed cross-coupling reactions of aryl bromides with trifluoromethyl aryl ketones via difluoroenol silyl or monofluoroenol silyl ethers
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Palladium-catalyzed cross-coupling reactions of α-aryl-β,β- difluoroenol silyl and α-aryl-β-fluoroenol silyl ethers with aryl bromides proceed smoothly with good functional compatibility. The Royal Society of Chemistry.
- Guo, Yong,Shreeve, Jean'ne M.
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p. 3583 - 3585
(2008/03/13)
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- Direct electrophilic α-fluorination of imines: Efficient synthesis of mono-and difluoroimines
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(Chemical Equation Presented) A mild and efficient procedure to synthesize α-fluoro- and α,α-difluoroimines was developed. Various N-alkylimines derived from acetophenones were successfully monofluorinated using NFSI (N-fluorobenzenesulfonimide) in a mixture of CH3CN and DMF at 0°C. Alternatively, the same procedure without DMF gave rise to difluorinated imines when performed at room temperature. The obtained α- and α,α-difluorinated imines were subsequently reduced to give the corresponding β-fluoro- and β,β-difluoroamines in good yield.
- Verniest, Guido,Van Hende, Eva,Surmont, Riccardo,De Kimpe, Norbert
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p. 4767 - 4770
(2007/10/03)
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- Reactions of enamines with selectfluor: A straightforward route to difluorinated carbonyl compounds
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Reactions of enamines, preformed from β-dicarbonyl and monocarbonyl compounds, with Selectfluor (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2] octane bis(tetrafluoroborate) under mild conditions (triethylamine (TEA) or molecular sieves) easily led to the corresponding difluorinated carbonyl compounds in high yields.
- Peng, Weimin,Shreeve, Jean'ne M.
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p. 5760 - 5763
(2007/10/03)
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- Fluorination of ketones using iodotoluene difluoride
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Fluorination of ketones was achieved by the reaction of silyl enol ethers with iodotoluene difluoride in the presence of BF3·OEt 2 and a Et3N·HF complex. Georg Thieme Verlag Stuttgart.
- Sato, Saeko,Yoshida, Masanori,Hara, Shoji
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p. 2602 - 2605
(2007/10/03)
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