- Nickel-Catalyzed Decarboxylative Cross-Coupling of Bicyclo[1.1.1]pentyl Radicals Enabled by Electron Donor-Acceptor Complex Photoactivation
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The use of bicyclo[1.1.1]pentanes (BCPs) as para-disubstituted aryl bioisosteres has gained considerable momentum in drug development programs. Carbon-carbon bond formation via transition-metal-mediated cross-coupling represents an attractive strategy to generate BCP-aryl compounds for late-stage functionalization, but these typically require reactive organometallics to prepare BCP nucleophiles on demand from [1.1.1]propellane. In this study, the synthesis and Ni-catalyzed functionalization of BCP redox-active esters with (hetero)aryl bromides via the action of a photoactive electron donor-acceptor complex are reported.
- Polites, Viktor C.,Badir, Shorouk O.,Keess, Sebastian,Jolit, Anais,Molander, Gary A.
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- Catalytic Enantioselective Direct Aldol Addition of Aryl Ketones to α-Fluorinated Ketones
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The catalytic enantioselective synthesis of α-fluorinated chiral tertiary alcohols from (hetero)aryl methyl ketones is described. The use of a bifunctional iminophosphorane (BIMP) superbase was found to facilitate direct aldol addition by providing the strong Br?nsted basicity required for rapid aryl enolate formation. The new synthetic protocol is easy to perform and tolerates a broad range of functionalities and heterocycles with high enantioselectivity (up to >99:1 e.r.). Multi-gram scalability has been demonstrated along with catalyst recovery and recycling. 1H NMR studies identified a 1400-fold rate enhancement under BIMP catalysis, compared to the prior state-of-the-art catalytic system. The utility of the aldol products has been highlighted with the synthesis of various enantioenriched building blocks and heterocycles, including 1,3-aminoalcohol, 1,3-diol, oxetane, and isoxazoline derivatives.
- Barber, David M.,Dixon, Darren J.,Thomson, Connor J.
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- Fluoroform: an Efficient Precursor for the Trifluoromethylation of Aromatic Esters by Sodium Diisopropylamide with Trialkylamines
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The trifluoromethanide anion is the postulated key intermediate in nucleophilic trifluoromethylation reactions. It is believed to be incompatible with Na+ cation due to the strong Na–F bond. However, herein we demonstrate that it could be prepared for the first time. Trialkylamines can be used as cation chelating agents to stabilize the isolated –CF3 ion to realize trifluoromethylation reaction. With this strategy, trifluoromethyl aromatic ketones could be effectively synthesized from fluoroform and aromatic esters with diisopropyl aminosodium (NaDA) and trialkylamines.
- Han, Zhaomeng,Chen, Sihan,Tu, Yongjun,Lian, Xiongdong,Li, Gongyong
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- Trifluoromethylation of Benzoic Acids: An Access to Aryl Trifluoromethyl Ketones
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The trifluoromethylation of benzoic acids with TMSCF3 was achieved through nucleophilic substitution with the use of anhydrides as an in situ activating reagent. Under the reaction conditions, a wide range of carboxylic acids including the bioactive ones worked well, thus providing a facile and efficient method for preparing aryl trifluoromethyl ketones from the readily available starting materials.
- Liu, Xue,Liu, Long,Huang, Tianzeng,Zhang, Jingjing,Tang, Zhi,Li, Chunya,Chen, Tieqiao
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supporting information
p. 4930 - 4934
(2021/06/30)
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- Selective Acylation of Aryl- A nd Heteroarylmagnesium Reagents with Esters in Continuous Flow
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A selective acylation of readily accessible organomagnesium reagents with commercially available esters proceeds at convenient temperatures and short residence times in continuous flow. Flow conditions allow us to prevent premature collapse of the hemiacetal intermediates despite noncryogenic conditions, thus furnishing ketones in good yields. Throughout, the coordinating ability of the ester and/or Grignard was crucial for the reaction outcome. This was leveraged by the obtention of several bisaryl ketones using 2-hydroxy ester derivatives as substrates.
- Heinz, Benjamin,Djukanovic, Dimitrije,Ganiek, Maximilian A.,Martin, Benjamin,Schenkel, Berthold,Knochel, Paul
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supporting information
p. 493 - 496
(2020/01/31)
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- Photoredox Generation of Carbon-Centered Radicals Enables the Construction of 1,1-Difluoroalkene Carbonyl Mimics
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Described is a facile, scalable route to access functional-group-rich gem-difluoroalkenes. Using visible-light-activated catalysts in conjunction with an arsenal of carbon-radical precursors, an array of trifluoromethyl-substituted alkenes undergoes radical defluorinative alkylation. Nonstabilized primary, secondary, and tertiary radicals can be used to install functional groups in a convergent manner, which would otherwise be challenging by two-electron pathways. The process readily extends to other perfluoroalkyl-substituted alkenes. In addition, we report the development of an organotrifluoroborate reagent to expedite the synthesis of the requisite trifluoromethyl-substituted alkene starting materials.
- Lang, Simon B.,Wiles, Rebecca J.,Kelly, Christopher B.,Molander, Gary A.
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p. 15073 - 15077
(2017/11/20)
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- Copper-catalyzed trifluoromethylation of N,N-dialkylhydrazones
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Mild and practical: Trifluoromethylation of (hetero)aromatic aldehyde N,N-dialkylhydrazones was achieved at room temperature by using Togni's trifluoromethylation reagent under CuCl catalysis (see scheme). This simple reaction is believed to occur by a CF3-radical-transfer mechanism and yields useful trifluoromethylated building blocks. Copyright
- Pair, Etienne,Monteiro, Nuno,Bouyssi, Didier,Baudoin, Olivier
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supporting information
p. 5346 - 5349
(2013/06/05)
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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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- Unusual behaviour of N-cinnamoyl-2-hydroxy-2- (trifluoromethyl)arylethylamines in Pictet-Gams cyclization. Synthesis of 2- styryl-5-aryl-5-trifluoromethyl-2-oxazolines
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Cyclization of N-acyl-2-hydroxy-2-(trifluoromethyl)arylethylamines 4 under Pictet-Gams conditions afforded 2-oxazolines 5 instead of the expected isoquinolines 6. The effect of the trifluoromethyl group on the result of the reaction is discussed.
- Poszavacz, Laszlo,Simig, Gyula
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p. 343 - 348
(2007/10/03)
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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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- Oxime insecticides
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Compounds with anthropodicidal activities having the general formula (1) STR1 and their isomeric forms wherein R represents F, Cl, Br, ethoxy, methoxy or propxy and n is an integer between 1 and 5; or R represents 3,4-methylenedioxyl; and R40 represents di- or trichloromethyl, fluorodichloromethyl or trifluoromethyl.
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