- Grafting organic and biomolecules on H-terminated porous silicon from a diazirine
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A diazirine compound, 1,4-(1-azi-2,2,2-trifluoroethyl)benzoic acid, was used as a stable carbene precursor to react with Si-H terminated porous silicon (PSi) under microwave irradiation. After formation of a molecular monolayer, the end carboxyl group was
- Wei, Shuai,Wang, Jing,Guo, Dong-Jie,Chen, Ya-Qing,Xiao, Shou-Jun
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Read Online
- Click-Addressable Cassette for Photoaffinity Labeling
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A small molecule 1 was designed to contain an alkyne, a trifluoromethyl phenyldiazirine, and a free piperidine-NH for facile conjugation to protein binding ligands. This "cassette" 1 was synthesized via a relatively direct route involving only routine steps. In this proof-of-concept study, putative ligands for carbonic anhydrase IX and for TrkC were conjugated to 1. Photoaffinity labeling was performed using purified extracellular regions of both these protein-receptors, and using cells that express these receptors (isolation via a pull-down procedure), labeling of the protein was observed in all four experiments.
- Zhao, Bosheng,Burgess, Kevin
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Read Online
- Highly enantioselective construction of CF3-bearing all-carbon quaternary stereocenters: Hiral spiro-fused bisoxazoline ligands with 1,1′-binaphthyl sidearm for asymmetric Michael-type Friedel-Crafts reaction
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A novel class of chiral spiro-fused bisoxazoline ligands possessing a deep chiral pocket was prepared. The developed ligands have been employed in the nickel-catalyzed highly enantioselective Michael-type Friedel-Crafts reaction, affording the products bearing a trifluoromethylated all-carbon quaternary stereocenter with moderate to excellent yields (up to 99%) and good to excellent enantioselectivies (up to > 99.9% ee). Moreover, a proposed model of chiral pocket revealed that the attack of indole from the Re-face of β-CF3-β-disubstituted nitroalkene was favorable.
- Bao, Robert Li-Yuan,Fu, Kang,Shi, Lei
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supporting information
(2021/11/27)
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- A Hammett Study of Clostridium acetobutylicum Alcohol Dehydrogenase (CaADH): An Enzyme with Remarkable Substrate Promiscuity and Utility for Organic Synthesis
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Described is a physical organic study of the reduction of three sets of carbonyl compounds by the NADPH-dependent enzyme Clostridium acetobutylicum alcohol dehydrogenase (CaADH). Previous studies in our group have shown this enzyme to display broad substrate promiscuity, yet remarkable stereochemical fidelity, in the reduction of carbonyl compounds, including α-, β- and γ-keto esters (d -stereochemistry), as well as α,α-difluorinated-β-keto phosphonate esters (l -stereochemistry). To better mechanistically characterize this promising dehydrogenase enzyme, we report here the results of a Hammett linear free-energy relationship (LFER) study across three distinct classes of carbonyl substrates; namely aryl aldehydes, aryl β-keto esters and aryl trifluoromethyl ketones. Rates are measured by monitoring the decrease in NADPH fluorescence at 460 nm with time across a range of substrate concentrations for each member of each carbonyl compound class. The resulting v 0 versus [S] data are subjected to least-squares hyperbolic fitting to the Michaelis-Menton equation. Hammett plots of log(V max) versus σ X yield the following Hammett parameters: (i) for p -substituted aldehydes, ρ = 0.99 ± 0.10, ρ = 0.40 ± 0.09; two domains observed, (ii) for p -substituted β-keto esters ρ = 1.02 ± 0.31, and (iii) for p -substituted aryl trifluoromethyl ketones ρ = -0.97 ± 0.12. The positive sign of ρ indicated for the first two compound classes suggests that the hydride transfer from the nicotinamide cofactor is at least partially rate-limiting, whereas the negative sign of ρ for the aryl trifluoromethyl ketone class suggests that dehydration of the ketone hydrate may be rate-limiting for this compound class. Consistent with this notion, examination of the 13 C NMR spectra for the set of p -substituted aryl trifluo romethyl ketones in 2percent aqueous DMSO reveals significant formation of the hydrate (gem -diol) for this compound family, with compounds bearing the more electron-withdrawing groups showing greater degrees of hydration. This work also presents the first examples of the CaADH-mediated reduction of aryl trifluoromethyl ketones, and chiral HPLC analysis indicates that the parent compound α,α,α-trifluoroacetophenone is enzymatically reduced in 99percent ee and 95percent yield, providing the (S)-stereoisomer, suggesting yet another compound class for which this enzyme displays high enantioselectivity.
- Berkowitz, David B.,Kudalkar, Gaurav P.,Lee, Joshua D.,Tiwari, Virendra K.
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supporting information
p. 237 - 247
(2020/02/18)
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- Palladium-catalyzed fluoroacylation of (Hetero)arylboronic acid with fluorothioacetates at ambient temperature
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A palladium-catalyzed fluoroacylation of (hetero)aryl boronic acid with the fluorothioacetates is described at ambient temperature. A variety of aryl, and heteroaryl boronic acids are compatible in the reaction, affording the corresponding fluoroalkyl ketones in moderate to good yields. Further late-stage di-, and trifluoroacylation of drug molecule clofibrate and estrone demonstrated the synthetic practicability of this protocol.2009 Elsevier Ltd. All rights reserved.
- Ban, Shu-Rong,Cao, Ya-Fang,Dai, Hui-Xiong,Wang, Xing,Xu, Hui,Yi, Xing
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supporting information
(2020/03/23)
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- Decarboxylative and Deaminative Alkylation of Difluoroenoxysilanes via Photoredox Catalysis: A General Method for Site-Selective Synthesis of Difluoroalkylated Alkanes
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A general method for site-selective difluoroalkylation of alkyl carboxylic redox esters with difluoroenoxysilanes through photoredox-catalyzed decarboxylative reaction has been developed. The reaction can also be extended to aliphatic amine derived pyridinium salts. This method has the advantages of high efficiency, mild reaction conditions, and broad substrate scope, including primary, secondary, and sterically hindered tertiaryl alkyl substrates, providing a general and practical route for applications in organic synthesis and pharmaceutical studies.
- Song, Heng,Cheng, Ran,Min, Qiao-Qiao,Zhang, Xingang
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supporting information
p. 7747 - 7751
(2020/10/09)
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- Engineering bromodomains with a photoactive amino acid by engaging 'Privileged' tRNA synthetases
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Site-specific placement of unnatural amino acids, particularly those responsive to light, offers an elegant approach to control protein function and capture their fleeting 'interactome'. Herein, we have resurrected 4-(trifluoromethyldiazirinyl)-phenylalan
- Wagner, Shana,Sudhamalla, Babu,Mannes, Philip,Sappa, Sushma,Kavoosi, Sam,Dey, Debasis,Wang, Sinan,Islam, Kabirul
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supporting information
p. 3641 - 3644
(2020/04/07)
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- Oxidation of α-trifluoromethyl and non-fluorinated alcohols: Via the merger of oxoammonium cations and photoredox catalysis
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We present an alcohol oxidation strategy to access α-trifluoromethyl ketones (TFMKs) merging catalytic oxoammonium cation oxidation with visible-light photoredox catalysis. This work uses 4-acetamido-(2,2,6,6-tetramethyl-piperidin-1-yl)oxyl as an organic oxidant capable of generating TFMKs in good yields. The methodology serves as an improvement over previous reports of an analogous oxidation strategy requiring superstoichiometric quantities of oxidant. Both primary and secondary non-fluorinated alcohols can also be oxidised in good yields.
- Pistritto, Vincent A.,Paolillo, Joshua M.,Bisset, Kathryn A.,Leadbeater, Nicholas E.
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supporting information
p. 4715 - 4719
(2018/07/06)
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- Visible light-promoted umpolung coupling of aryl tri-/difluoroethanones with 2-alkenylpyridines
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Tertiary alcohols bearing a trifluoromethyl group are of considerable medicinal interest. Using an umpolung strategy, we herein report the first intermolecular reductive cross-coupling of aryl tri-/difluoroethanones with 2-alkenylpyridines with the aid of a Br?nsted acid catalyst upon visible-light irradiation. This metal-free reaction is operationally simple and performed at ambient temperature, allowing access to desired tertiary alcohols with tri-/difluoromethyl groups in moderate to excellent yields. The commercially available and easily handled Hantzsch ester effectively serves as an electron donor, as well as a hydrogen atom source.
- Xu, Xiao,Min, Qing-Qiang,Li, Na,Liu, Feng
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supporting information
p. 11017 - 11020
(2018/10/08)
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- Rapid Mapping of Protein Interactions Using Tag-Transfer Photocrosslinkers
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Analysing protein complexes by chemical crosslinking-mass spectrometry (XL-MS) is limited by the side-chain reactivities and sizes of available crosslinkers, their slow reaction rates, and difficulties in crosslink enrichment, especially for rare, transie
- Horne, Jim E.,Walko, Martin,Calabrese, Antonio N.,Levenstein, Mark A.,Brockwell, David J.,Kapur, Nikil,Wilson, Andrew J.,Radford, Sheena E.
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supporting information
p. 16688 - 16692
(2018/11/27)
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- Spatiotemporal Control of Pre-existing Alkene Geometry: A Bio-Inspired Route to 4-Trifluoromethyl-2H-chromenes
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Routes to prepare C4-trifluoromethyl analogues of the 2H-chromene scaffold are scarce: this is particularly striking given the importance of fluorine in pharmaceutical development. To address this limitation, a facile strategy has been developed that is reliant on catalytic, geometric isomerization of easily accessible allylic alcohols (up to >95:5) followed by intramolecular cyclization via Pd catalysis (up to 96%). This concise biomimetic approach emulates the photoisomerization/cyclization cascade inherent to phenylpropanoid biosynthesis.
- Fa?bender, Svenja I.,Metternich, Jan B.,Gilmour, Ryan
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supporting information
p. 724 - 727
(2018/02/09)
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- New entry for fluorinated carbocycles: Unprecedented 3,6-disubstituted 1,1,2,2-tetrafluorocyclohexane derivatives
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The synthetic protocols for symmetrical/unsymmetrical 3,6-disubstituted 1,1,2,2-tetrafluorocyclohexane molecules were successfully established for the first time. Some of thus obtained tetrafluorinated cyclohexanes underwent recrystallization to afford trans-configured products preferentially. One of the unsymmetrical trans-disubstituted tetrafluorocyclohexanes, trans-1-ethyl-2,2,3,3-tetrafluoro-4-[4-(trans-4-n-propylcyclohex-1-yl)phenyl]cyclohexane, was found to possess a low birefringence Δn (0.073) and a large negative dielectric anisotropy Δε (–9.4) in a binary mixture system, which were very prominent as characteristics of LC molecules in VA-mode driving LC displays.
- Yamada, Shigeyuki,Hashishita, Shohei,Konishi, Hideaki,Nishi, Yuji,Kubota, Toshio,Asai, Tomoyuki,Ishihara, Takashi,Konno, Tsutomu
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- Domino C-F Bond Activation of the CF3 Group: Synthesis of Fluorinated Dibenzo[a,c][7]annulenes from 2-(Trifluoromethyl)-1-alkenes and 2,2′-Diceriobiaryls
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The construction of ring-fluorinated seven-membered carbocycles was readily achieved via the domino SN2′-type/SNV reaction between 2-(trifluoromethyl)-1-alkenes and 1,4-carbodianions. The SN2′-type reaction of 2-(trifluoromethyl)-1-alkenes with 2,2′-diceriobiaryls generated the intermediary 1,1-difluoro-1-alkenes bearing a monoceriobiaryl moiety, which in turn underwent intramolecular SNV reaction to afford fluorinated 5H-dibenzo[a,c][7]annulenes.
- Fujita, Takeshi,Takazawa, Marina,Sugiyama, Kazuki,Suzuki, Naoto,Ichikawa, Junji
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supporting information
p. 588 - 591
(2017/02/10)
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- Copper-Mediated Trifluoroacetylation of Arenediazonium Salts with Ethyl Trifluoropyruvate
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A copper-mediated trifluoroacetylation of various arenediazonium salts with ethyl trifluoropyruvate is reported. The reaction proceeded smoothly under mild conditions at room temperature giving trifluoromethyl aryl ketones in moderate to good yields. A variety of functional groups, including methoxy, hydroxy, ester, ketone, trifluoromethyl, and halide groups, were well tolerated. A possible reaction mechanism involving an aryl radical intermediate was proposed and supported by experimental evidence. This reaction provides a new route to trifluoromethyl aryl ketones, notable synthetic targets, from the corresponding anilines.
- Wu, Wei,Tian, Qinli,Chen, Taotao,Weng, Zhiqiang
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supporting information
p. 16455 - 16458
(2016/11/11)
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- Catalytic highly enantioselective transfer hydrogenation of β-trifluoromethyl nitroalkenes. An easy and general entry to optically active β-trifluoromethyl amines
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In the presence of a thiourea catalyst, β-CF3 nitroalkenes react with Hantzsch esters in a highly enantioselective fashion, giving a broad range of β-CF3 amine precursors with a tertiary stereocentre at the β-position. This reaction
- Martinelli, Emilie,Vicini, Anna Chiara,Mancinelli, Michele,Mazzanti, Andrea,Zani, Paolo,Bernardi, Luca,Fochi, Mariafrancesca
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supporting information
p. 658 - 660
(2015/01/09)
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- One-pot multistep synthesis of trisubstituted alkenes from N -tosylhydrazones and alcohols
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A one-pot procedure for the synthesis of trisubstituted alkenes from N-tosylhydrazones and alcohols is reported. This procedure combines the aerobic oxidation reaction and Wittig reaction in one pot, which avoids using of environmentally toxic oxidants and isolation of the intermediates. The simple procedure makes it very attractive for the synthesis of trisubstituted alkenes when alcohols are used as starting materials. A variety of trisubstituted alkenes as well as trifluoromethyl-substituted alkenes were obtained in moderate to good yields (up to 84%) with good E-selectivity (up to 99%). Georg Thieme Verlag Stuttgart.New York.
- Sha, Qiang,Wei, Yunyang
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supporting information
p. 2353 - 2361
(2014/11/08)
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- Selective CH Functionalization of Methane, Ethane, and Propane by a Perfluoroarene Iodine(III) Complex
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Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic (trifluoroacetic acid) solvent. The reaction is highly selective for ester formation (>99 %). In the case of ethane, greater than 0.5 M EtTFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism. Gas up: Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate (TFA) esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic solvent (HTFA). The reaction is highly selective, and for ethane, greater than 0.5 M Et=TFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism.
- Konnick, Michael M.,Hashiguchi, Brian G.,Devarajan, Deepa,Boaz, Nicholas C.,Gunnoe, T. Brent,Groves, John T.,Gunsalus, Niles,Ess, Daniel H.,Periana, Roy A.
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supporting information
p. 10490 - 10494
(2016/02/18)
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- Catalytic asymmetric hydrogenation of α-CF3- or β-CF3-Substituted acrylic acids using Rhodium(I) complexes with a combination of chiral and achiral ligands
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Only the mixture works! Acrylic acid derivatives with CF3 substituents in α or β position were efficiently hydrogenated in the presence of a RhI complex with a chiral secondary phosphine oxide (SPO; see scheme) and an achiral Ph3P as ligands. The corresponding propanoic acid derivatives were obtained with generally high conversion (>99 %) and high enantioselectivity (92->99 %). Copyright
- Dong, Kaiwu,Li, Yang,Wang, Zheng,Ding, Kuiling
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supporting information
p. 14191 - 14195
(2014/01/06)
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- Highly efficient synthesis of aryl and heteroaryl trifluoromethyl ketones via o-iodobenzoic acid (IBX)
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A two-step process for the synthesis of aryl and heteroaryl trifluoromethyl ketones from the corresponding aldehydes is described. Trifluoromethyl alcohols were prepared from aryl and heteroaryl aldehydes in excellent yields using catalytic amount of K2CO3. The trifluoromethyl alcohols were then oxidized conveniently and efficiently by o-iodoxybenzoic acid (IBX) under mild conditions to get the desired functionalized aryl and heteroaryl trifluoromethyl ketones.
- Cheng, Huicheng,Pei, Yu,Leng, Faqiang,Li, Jingya,Liang, Apeng,Zou, Dapeng,Wu, Yangjie,Wu, Yusheng
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p. 4483 - 4486
(2013/07/26)
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- A coupling of benzamides and donor/acceptor diazo compounds to form γ-lactams via Rh(III)-catalyzed C-H activation
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The coupling of O-pivaloyl benzhydroxamic acids with donor/acceptor diazo compounds provides isoindolones in high yield. The reaction tolerates a broad range of benzhydroxamic acids and diazo compounds, including substituted 2,2,2-trifluorodiazoethanes. Mechanistic experiments suggested that C-H activation is turnover-limiting and irreversible and that insertion of the diazo compound favors electron-deficient substrates.
- Hyster, Todd K.,Ruhl, Kyle E.,Rovis, Tomislav
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supporting information
p. 5364 - 5367
(2013/05/22)
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- Oxidation of α-trifluoromethyl alcohols using a recyclable oxoammonium salt
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A simple, mild method for the oxidation of α-trifluoromethyl alcohols to trifluoromethyl ketones (TFMKs) using the oxoammonium salt 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (1) is described. Under basic conditions, oxidation proceeds rapidly and affords good to excellent yields of TFMKs, without concomitant formation of the hydrate. The byproduct of the oxidation, 4-acetylamino-2,2,6,6-tetramethyl-1- piperidinyloxy (1c), is easily recovered and can be conveniently reoxidized to regenerate the oxoammonium salt.
- Kelly, Christopher B.,Mercadante, Michael A.,Hamlin, Trevor A.,Fletcher, Madison H.,Leadbeater, Nicholas E.
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p. 8131 - 8141
(2013/01/15)
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- Tri- and tetravalent photoactivable cross-linking agents
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A modular synthesis of photoactivable cross-linking agents is described, using an aromatic core, di- or triethyleneglycol spacers and photoaffinity labeling synthons that feature either perfluorophenyl azide or aryl(trifluoromethyl)diazirine motifs. Symmetrical and nonsymmetrical trivalent structures were obtained from phloroglucinol and dopamine, respectively. Symmetrical tetravalent structures resulted from the coupling of two dopamine derivatives with oxalyl chloride. Georg Thieme Verlag Stuttgart New York.
- Welle, Alexandre,Billard, Francois,Marchand-Brynaert, Jacqueline
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supporting information; experimental part
p. 2249 - 2254
(2012/10/08)
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- PROCESS TO OBTAIN A TRIFLUOROMETHYLATING COMPOSITION
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Process to obtain a trifluoromethylating composition which comprises the reaction between a copper (I) source and a base in the presence of a solvent and between the resulting cuprating reagent with fluoroform.
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Page/Page column 58
(2012/09/11)
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- Silver compounds in synthetic chemistry. Part 5: Selective syntheses of trifluoromethylketones, RCOCF3, from trifluoromethylsilver, AgCF3, and corresponding acyl chlorides, RCOCl
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Trifluoromethylketones of aromatics, heteroaromatics and olefins are formed selectively from reactions of trifluoromethylsilver and the corresponding carboxylic acid chlorides in moderate to excellent yields. The conditions chosen are dependent on the nature of the acyl chloride. Attempts to prepare alkyl(trifluoromethyl)ketones yielded product mixtures of the corresponding acyl fluorides, trifluoromethyl-, pentafluoroethyl- and n-heptafluoropropyl ketones.
- Kremlev, Mikhail M.,Mushta, Aleksej I.,Tyrra, Wieland,Naumann, Dieter,Fischer, Hendrik T.M.,Yagupolskii, Yurii L.
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p. 1385 - 1389
(2008/09/18)
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- Synthesis and biological evaluation of photoaffinity labeled fusidic acid analogues
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Novel photoaffinity labeled fusidic acid analogues were obtained by a synthetic sequence employing a Wittig reaction between a fusidic acid aldehyde and benzyl bromides in the key step. Three commonly used photoreactive groups, benzophenone, trifluoromethyldiazirine, and aryl azide, were used. The photoaffinity labeled fusidic acid analogues demonstrated a potent antibacterial activity (MIC 0.016-4 μg/mL) and therefore represent a potential tool for the elucidation of the interactions between fusidic acid and its receptor EF-G.
- Riber, Ditte,Venkataramana, Musturi,Sanyal, Suparna,Duvold, Tore
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p. 1503 - 1505
(2007/10/03)
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- Design, synthesis and evaluation of novel hydroxyamides as orally available anticonvulsants
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Themisone, also known as Atrolactamide, was found, in the 1950s, to be a very potent anticonvulsant. It was hypothesized that the -CF3 substitution would maintain the anticonvulsant activity. Anticonvulsant testing of our novel compounds by the
- Schenck, Hilary A.,Lenkowski, Paul W.,Choudhury-Mukherjee, Indrani,Ko, Seong-Hoon,Stables, James P.,Patel, Manoj K.,Brown, Milton L.
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p. 979 - 993
(2007/10/03)
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- A general method of halogenation for synthesis of α-halodifluoromethyl ketones and [18F]-labeled trifluoromethyl ketones
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A convenient general method of halogenations suitable for synthesis of α-halodifluoromethyl ketones is reported. Reaction of 2,2-difluoro-1-aryl-1-trimethylsiloxyethenes (difluoro silyl enol ethers) (2a-e) with halogens at low temperature (-30 to -78 °C) produced a high yield of α-halodifluoromethyl ketones (1a-j). This one-step simple method can be highly useful for synthesis of [18F]-labeled α-trifluoromethyl ketones.
- Prakash, G.K. Surya,Hu, Jinbo,Alauddin, Mian M.,Conti, Peter S.,Olah, George A.
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p. 239 - 243
(2007/10/03)
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- Oxime derivatives and the use thereof as latent acids
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Compounds of formula I, II and III, wherein wherein R1is for example hydrogen, C1-C12alkyl, C3-C30cycloalkyl, C2-C12alkenyl, C4-C8cycloalkenyl, phenyl, whic
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- Ginkgolide derivatives for photolabeling studies: Preparation and pharmacological evaluation
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The terpene trilactones (TTLs), ginkgolides and bilobalide, are structurally unique constituents of Ginkgo biloba extracts, which exhibit various neuromodulatory properties. Although the TTLs are believed to be responsible for some of these effects, the s
- Str?mgaard, Kristian,Saito, D. Roland,Shindou, Hideo,Ishii, Satoshi,Shimizu, Takao,Nakanishi, Koji
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p. 4038 - 4046
(2007/10/03)
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- Diels-Alder reactions of β-trifluoroacetylvinylsulfones
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Diels-Alder reactions of β-trifluoroacetylvinylsulfones with 1,3-dienes in CH2Cl2 afforded corresponding mono- and polycycloadducts. A possibility of stereo- and regioselective cycloaddition was investigated. Elimination of sulfonyl group from cycloadducts leads to α,β-unsaturated trifluoromethylketones in good yields.
- Krasovsky, Arkady L,Nenajdenko, Valentine G,Balenkova, Elizabeth S
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p. 201 - 209
(2007/10/03)
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- Synthesis of trifluoromethyl ketones by palladium-catalyzed cross-coupling reaction of phenyl trifluoroacetate with organoboron compounds
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Cross-coupling reaction of aryl trifluoroacetates with organoboron compounds catalyzed by palladium complexes gives trifluoromethyl ketones in moderate to excellent yields under mild conditions. The catalytic process has been designed on the basis of fundamental studies dealing with oxidative addition of phenyl trifluoroacetate to a Pd(0) complex to give a (phenoxo)(trifluoroacetyl)palladium(II) complex and its subsequent reaction with phenylboronic acid to liberate phenyl trifluoromethyl ketone. The catalytic cycle is proposed to be composed of (a) oxidative addition of the ester to give acyl(aryloxo)palladium intermediate, (b) the subsequent transmetallation with arylboron compounds, and (c) reductive elimination. Palladium(0) complexes, as well as catalysts prepared in situ from palladium acetate and 3 molar amounts of tributylphosphine or phosphite at room temperature, serve as convenient and effective catalysts. The process is applicable to a wide range of phenyl- and naphthylboronic acids to give various aryl trifluoromethyl ketones under mild conditions. Aryl perfluoroalkyl ketone derivatives can be similarly prepared in high yields from various phenyl perfluoroalkanecarboxylates and arylboronic acids.
- Kakino,Shimizu,Yamamoto
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p. 371 - 376
(2007/10/03)
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- Re-investigation of the coupling reaction of 2-aryl-1,1-dibromo-3,3,3- trifluoropropenes. Preparation of perfluoroalkylated [3]cumulenes
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The coupling reaction of perfluoroalkylated 2-aryl-1,1-dibromoalkenes using zinc and copper(1) bromide gave stereoisomeric mixtures of [3]cumulenes and [4]radialenes. The ratio of [3]cumulenes and [4]radialenes mainly depended upon the reaction temperature and the electronic character of the aryl group. When the coupling reaction was carried out at -40 °C, (E)- and (Z)-[3]cumulenes were obtained in good selectivity and only trace amounts of [4]radialenes were detected by a 19FNMR analysis. On the other hand, a similar reaction at -60 °C afforded a considerable amount of [4]radialene isomers. When the cis-[3]cumulenes were heated at an appropriate temperature, selective isomerization to trans-[3]cumulenes occurred.
- Uno, Hidemitsu,Nibu, Nobumasa,Misobe, Noboru
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p. 1365 - 1375
(2007/10/03)
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- The oxidation of secondary alcohols by potassium tetraoxoferrate(VI)
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The kinetics of the oxidation of 2-propanol, 1,1,1-trifluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 1-phenyl-2,2,2-trifluoroethanol, 1-(4-methylphenyl)-2,2,2-trifluoroethanol, 1-(3-bromophenyl)-2,2,2-trifluoroethanol, and 1-(3-nitrophenyl)-2,2,2-trifluoroethanol by potassium tetraoxoferrate(VI) have been studied under basic conditions. The products are ketones, formed in almost quantitative yields, iron(III) hydroxide, and dioxygen. The reactions are characterized by substantial enthalpies of activation (40-60 kJ/mol), very unfavorable entropies of activation, large primary deuterium isotope effects, and a positive Hammett p value. Both acid and base catalysis are observed. Acid catalysis is attributed to formation of a more reactive oxidant, HFeO4-, at low pH. Base catalysis is attributed partly to the conversion of the reductants to alkoxide ions at high pH, and partly to the reaction of hydroxide ion with tetraoxoferrate(VI) to give a five-coordinated species, HOFeO43-, that reacts rapidly with nucleophiles. A reaction mechanism involving formation of an intermediate ferrate ester is proposed.
- Norcross, Bruce E.,Lewis, William C.,Gai, Huiffa,Noureldin, Nazih A.,Lee, Donald G.
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p. 129 - 139
(2007/10/03)
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- Process for preparing trifluoromethyl ketones
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A process is described for preparing trifluoromethyl ketones of the formula I STR1 where R has the given meanings, wherein an alcohol of the formula II STR2 is reacted with a compound of the formula IV where n has the given meaning.
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- A simple method for the preparation of aryl trifluoromethyl ketones
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4-Dimethylamino-1-trifluoroacetylpyridinium trifluoroacetate (2) is an effective, easy to handle and stable trifluoroacetylation agent. Aryl trifluormethyl ketones 4 are obtained in good yields by reaction of 2 with aromatic compounds 3 in the presence of aluminum chloride.
- Simchen, Gerhard,Schmidt, Andreas
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p. 1093 - 1094
(2007/10/03)
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- Stereocontrolled synthesis of p-substituted trifluoromethylbenzylic alcohol derivatives of high optical purity by the Baker's yeast reduction
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The enantioselectivity of the bakers' yeast reduction of p-substituted trifluoroacetylbenzene derivatives could be improved by the introduction of some functional groups at the para-position to give the corresponding (R)-trifluoromethyl-substituted benzyl
- Fujisawa,Ichikawa,Shimizu
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p. 1237 - 1240
(2007/10/02)
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- Insecticidal ethers
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This invention relates to novel fluorinated ethers, useful as insecticides and acaricides, to processes and intermediates for their preparation, to insecticidal and acaricidal compositions thereof and to methods of combating and controlling insect and acarine pests therewith.
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- Die Reacktionen von Bis(perfluoralkyl)cadmium-Komplexen mit Arylcarbonsaeurechloriden: Synthese von Aryl(perfluoralkyl)ketonen, (Perfluoralkyl-dihydropyridin)arylcarbonsaeureamiden, α,α-Bis(trifluormethyl)benzylalkoholen und Benzoesaeure-α,α-bis(trifluormethyl)benzylestern
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Perfluoroalkylcadmium complexes react with aroyl halides in the presence of strong bases such as pyridine to give the corresponding ketones ArCORf (which can be isolated in 5-51percent yield) and (perfluoroalkyldihydropyridine)aroylamides.The pure substances are obtained by chromatography.Aroyl fluorides and α,α-bis(trifluoromethyl)benzyl alcohols and benzoic acid-α,α-bis(trifluoromethyl)benzyl esters can be isolated as by-products.The dependency of the products formed on the kind of bases used as well as the reaction mechanisms are described.All products were identified by their 19F, 1H, 13C NMR, mass and IR spectra, and by elemental analysis.
- Naumann, Dieter,Finke, Martina,Lange, Horst,Dukat, Wolfgang,Tyrra, Wieland
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p. 215 - 237
(2007/10/02)
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- REACTIONS OF 1-CHLOROALKYL ISOCYANATES WITH THIOURETHANES
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1-Chloroalkyl isocyanates react with thiourethanes to gives N-acylation products, namely, N-(N-alkylidenaminocarbonyl)thiourethanes, which exist in solution in tautomeric equilibrium with S-(1-isocyanatoalkyl)isothiourethanes.These tautomeric transformation occur in the C=N-C azaallylic system involving a new anionotropic migrant, namely, the thiocarbamyl group.The reactions of these tautomeric compounds with water, alcohols, phenol, and primary amines proceed with the participation of the azomethine form, while the reactions with secondary amines involve the isocyanate form.
- Vovk, M. V.,Davidyuk, Yu. N.,Chernega, A. N.,Tsymbal, I. F.,Samarai, L. I.
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p. 1635 - 1643
(2007/10/02)
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- A Convenient Trifluoroacetylation of Arenes with 2-(Trifluoroacetoxy)pyridine
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2-(Trifluoroacetoxy)pyridine (TFAP) is useful for trifluoroacetylating arenes under Friedel-Crafts conditions.Benzene, alkylbenzenes, naphthalene, and dibenzofuran have reacted with TFAP in the presence of aluminum chloride in dichloromethane to give the corresponding trifluoromethyl aryl ketones in good isolated yields.
- Keumi, Takashi,Shimada, Masakazu,Takahashi, Masahiro,Kitajima, Hidehiko
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p. 783 - 786
(2007/10/02)
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- 1-(ACYLOXY)ALKYL ISOCYANATES. II. REACTIONS WITH PROTON-CONTAINING NUCLEOPHILIC REAGENTS
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The reactions of 1-(acyloxy)alkyl isocyanates with water, alcohols, phenols, amines, and alkane- and arenethiols lead to the formation of ketones, N-alkylideneurethanes, N-alkylideneureas, and 1-alkylthio- and 1-arylthioalkyl isocyanates respectively.
- Vovk, M. V.,Dorokhov, V. I.,Samarai, L. I.
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p. 675 - 679
(2007/10/02)
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- Swern Oxidation of Diaziridines to Diazirines
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The trifluoromethyldiaziridines (1) - (6) have been converted into the photolabile diazirines (7) - (12) using dimethyl sulphoxide-oxalyl chloride; several of these diazirines have previously been used as intermediates in the preparation of photoaffinity
- Richardson, Stewart K.,Ife, Robert J.
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p. 1172 - 1174
(2007/10/02)
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- β-DEUTERIUM KINETIC ISOTOPE EFFECTS IN THE SOLVOLYSIS OF 2-ARYL-1,1,1-TRIFLUORO-2-PROPYL TOSYLATES AND OF 2-ARYL-2-PROPYL p-NITROBENZOATES. EVIDENCE FOR A VARIATION OF THE CONTRIBUTION OF α-METHYL SUBSTITUENT IN STABILIZING CATIONIC REACTION CENTERS WITH DIFFERENT ELECTRON DEMAND
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A very high β-deuterium kinetic isotope effect, k(CH3)/k(CD3)=2.13 at 60 deg C, was found for the solvolysis of 2-(3'-chlorophenyl)-1,1,1-trifluoro-2-propyl tosylate (2c) and the α-CD3 analogue (4c), and the effect decreased with increasing electron attracting of the substituent on the aromatic ring which showed the variation of the contribution of α-methyl group to the stabilization of the cationic reaction center in the transition state.
- Liu, Kwang-Ting,Wu, Yuh Wern
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p. 3623 - 3626
(2007/10/02)
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- 4-(1-Azi-2,2,2-trifluoroethyl)benzoic Acid, a Highly Photolabile Carbene Generating Label Readily Fixable to Biochemical Agents
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The title compound is synthesized starting from either 4-bromobenzyl tert butyldimethylsilyl ether (5b) or 4-bromobenzyl tert-butyl ether (5c) or - most simply - from 4-bromotoluene (5a).In the first step Br was replaced by Li using n-butyllithium, then the organometallic compounds were converted into the respective trifluoroacetophenones 6a - c with N-trifluoroacetylpiperidine.The azi moiety (diazirine) was prepared from the oximes 7a - c via O-tosyloximes 8a - c plus ammonia yielding the diaziridines 9a - c and oxidation of the latter with Ag2O.Oxidation by permanganate - of the ethers after acidic cleavage - yields the title compound 12.On irradation (λ > 300 nm) 12 by elimination of N2 with a half-life period of 22 s generates the corresponding carbene.At the same time from 12 with ca. 20percent the yellow isomeric 4-(1-diazo-2,2,2-trifluoroethyl)benzoic acid (20) is formed which is photolyzed generating the same carbene as 12.The synthesis of 20 is described starting from 4-bromobenzaldehyde. - The diazirine 12 as its N-hydroxysuccinimide ester 13, or using other methods of amide synthesis, can readily be coupled to amino functions of biochemically interesting agents thus forming photoaffinity labels.
- Nassal, Michael
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p. 1510 - 1523
(2007/10/02)
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- REGIOSPECIFIC SYNTHESIS OF AROMATIC COMPOUNDS VIA ORGANOMETALLIC INTERMEDIATES. I. para-SUBSTITUTED BENZENES
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Para-substituted benzene compounds, p-XC6H4X' (X = CF3C(O) and X' = CH3, CO2H, C(O)CF3, C(O)CH3, C(O)H and SH) have been prepared via sequential metal-halogen exchange reactions between p-BrC6H4Br and n-C4H9Li and the appropriate electrophiles.Low reaction temperature is critical to stabilization of the various intermediates.The CF3 group has a pronounced effect on providing stability to the lithium hemiketal intermediates.
- Chen, Loomis S.,Chen, Grace J.,Tamborski, Christ
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p. 139 - 148
(2007/10/02)
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- Charge-Transfer Quenching of Triplet α-Trifluoroacetophenones
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The effects of ring substituents and of aromatic quenchers on the photoreduction by toluene of α,α,α-trifluoroacetophenone (AF3) have been measured.A plot of log kCT vs. ionization potential of the donor indicates that ΔGCT equals 22percent ΔG for the full electron transfer.A corresponding plot of log kCT vs. the triplet state reduction potential of ring-substituted AF3's, if analyzed as linear, would indicate that there is no intrinsic difference in reactivity between n,?* and ?,?* triplets but would also indicate that ΔGCT equals 42percent ΔG.The discrepancy between the 22 and 42percent is suggested to involve differing reactivities of n,?* and ?,?* triplets.If n,?* triplets are substantially more reactive, the plot vs. triplet reduction potential is expected to curve upward as the equilibrium population of n,?* triplet increases with substitution.
- Wagner, Peter J.,Lam, Henry M. H.
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p. 4167 - 4172
(2007/10/02)
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