- 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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- Synthesis of trifluoromethyl ketones by nucleophilic trifluoromethylation of esters under a fluoroform/KHMDS/triglyme system
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A straightforward method that enables the formation of biologically attractive trifluoromethyl ketones from readily available methyl esters using the potent greenhouse gas fluoroform (HCF3, HFC-23) was developed. The combination of fluoroform and KHMDS in triglyme at ?40 °C was effective for this transformation, with good yields as high as 92%. Substrate scope of the trifluoromethylation procedure was explored for aromatic, aliphatic, and conjugated methyl esters. This study presents a straightforward trifluoromethylation process of various methyl esters that convert well to the corresponding trifluoromethyl ketones. The tolerance of various pharmacophores under the reaction conditions was also explored.
- Fujihira, Yamato,Liang, Yumeng,Ono, Makoto,Hirano, Kazuki,Kagawa, Takumi,Shibata, Norio
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supporting information
p. 431 - 438
(2021/03/20)
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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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- N-phenyl-N-p-toluenesulfonyl trifluoroacetamide (NTFTS) and application
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The invention belongs to the technical field of medical chemical engineering intermediates and related chemistry, and relates to N-phenyl-N-p-toluenesulfonyl trifluoroacetamide (NTFTS) and application. The N-phenyl-N-p-toluenesulfonyl trifluoroacetamide is taken as a trifluoroacetylation reagent, reacts with an arylboronic acid derivative in an anhydrous organic solvent under the action of a metalcatalyst, a ligand and an alkali, and is efficiently and highly selectively converted into a trifluoroacetophenone compound. According to a synthesis method of the trifluoroacetophenone compound, involved in the invention, reaction steps are few; the NTFTS which is stable in use, easy to store, cheap and easy to get is taken as a trifluoroacetyl source; environmental friendliness is realized; reaction conditions are mild; operation is easy; a high-yield and high-selectivity target product is obtained and has relatively good industrial production value and practical application value. The trifluoroacetophenone compound synthesized by utilizing the method can be further subjected to a functionalization reaction, and can be widely applied to the synthetic fields of medicine, pesticide, bioactive molecules, functional material molecules and the like.
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Paragraph 0048-0051
(2019/08/02)
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- Enabling the Cross-Coupling of Tertiary Organoboron Nucleophiles through Radical-Mediated Alkyl Transfer
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The construction of quaternary centers is a common challenge in the synthesis of complex materials and natural products. Current cross-coupling strategies that can be generalized for setting these centers are sparse and, when known, are typically predicated on the use of reactive organometallic reagents. To address this shortcoming a new, photoredox-Ni dual catalytic strategy for the cross-coupling of tertiary organoboron reagents with aryl halides is reported. In addition to details on the cross-coupling scope and limitations, full screening efforts and mechanistic experiments are communicated.
- Primer, David N.,Molander, Gary A.
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supporting information
p. 9847 - 9850
(2017/08/02)
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- Palladium-catalyzed carbonylative coupling of aryl iodides with an organocopper reagent: A straightforward procedure for the synthesis of aryl trifluoromethyl ketones
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A palladium-catalyzed carbonylative coupling of aryl iodides with a (trifluoromethyl)copper reagent has been developed. A wide range of substrates have been transformed into their corresponding trifluoromethyl ketones in good to excellent yields under mild conditions with high efficiency and excellent functional-group compatibility. Preliminary mechanistic investigations suggest that the transmetallation of an acylpalladium intermediate with the (trifluoromethyl)copper reagent seems to be involved in the catalytic cycle. Notably, this report represents one of the few studies on carbonylative coupling with organocopper reagents.
- Zhu, Fengxiang,Yang, Guangfu,Zhou, Shaolin,Wu, Xiao-Feng
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p. 57070 - 57074
(2016/07/07)
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- A Weinreb amide approach to the synthesis of trifluoromethylketones
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A novel route to access trifluoromethylketones (TFMKs) from Weinreb amides is reported. This represents the first documented case of the Ruppert-Prakash reagent (TMS-CF3) reacting in a constructive manner with an amide and enables synthesis of TMFKs without risk of over-trifluoromethylation.
- Rudzinski, Diandra M.,Kelly, Christopher B.,Leadbeater, Nicholas E.
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supporting information
p. 9610 - 9612
(2012/10/29)
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- Palladium-catalyzed regio- and stereoselective formate reduction of fluorine-containing allylic mesylates. A new entry for the construction of a tertiary carbon attached with a fluoroalkyl group
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The regioselective palladium-catalyzed formate reduction of γ-fluoroalkylated allylic esters is described. Reduction of the allylic esters under the influence of palladium with a monodentate phosphine ligand proceeded preferentially at the γ position, the corresponding reduction products with a fluoroalkyl group at the tertiary carbon being afforded in high yields. When the chiral allylic ester was employed, complete chirality transfer was observed, leading to the optically active materials in high yields.
- Konno, Tsutomu,Takehana, Tsuyoshi,Mishima, Makoto,Ishihara, Takashi
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p. 3545 - 3550
(2007/10/03)
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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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- A Mild 10-I-4 Iodinane Oxide Oxidant for Primary and Secondary Alcohols
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Iodinane oxide 4 midly and rapidly oxidizes primary and secondary alsohols to their corresponding carbonyl products in excellent yield.Oxidations are carried out in CH2Cl2 at room temperature using 1.1 equivalent of oxidant.Other non-hydroxylic organic solvents may also be used.
- Stickley, Sharon H.,Martin, J. C.
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p. 9117 - 9120
(2007/10/02)
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- Hydration of Trifluoroacetophenone Derivatives as Studied by IR Spectroscopy
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The characteristics of the hydration reaction of four trifluoroacetophenone (L) derivatives were determined by IR spectroscopy.A correlation was found between the position of the O-H band maximum for the hydrated L form and the Hammett constant of the sub
- Bart, T. Ya.,Denisova, A. S.,Karavan, V. S.
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p. 1369 - 1371
(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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- Extent of Charge Transfer in the Photoreduction of Phenyl Ketones by Alkylbenzenes
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Rate constants for triplet-state reaction of various ring-substituted benzophenones (BPs), acetophenones (APs), and α,α,α-trifluoroacetophenones (TFAs) with toluene and p-xylene have been determined by a combination of flash kinetics, steady-state quenching, and quantum yield measurements.The relative amounts of primary and tertiary radicals formed by reaction of the same ketons with p-cymene have also been measured.For all three types of ketones, rate constants correlate well with triplet ketone reduction potentials.The magnitude of the kinetic isotope effects observed with toluene-d8 and p-xylene-d10 diminishes as the ketones become easier to reduce.All of the ketone triplets react with alkylbenzenes primarily by a charge-transfer mechanism, with the rate-determining step changing from complexation to hydrogen transfer as the ketones become harder to reduce.The least reactive AP triplets probably react significantly via simple hydrogen atom abstraction as well.Those ketones with n,?* lowest triplets (all BPs and some APs) react with p-cymene to give primary/tertiary radical ratios that vary no more than a factor of 2 from the 0.40 value displayed by tert-butoxy radicals; those with ?,?* lowest triplets (TFAs and some APs) give ratios that favor primary radicals and that vary by an order of magnitude with the triplet ketone reduction potential.The variation in cymene product ratios reflect different orientations for attack on cymene by n,?* and ?,?* triplets and differing degrees of partial electron transfer within the exciplexes, which are not tight radical ion pairs.The variation seen for ?,?* triplets represents a stereoelectronic effect within face-to-face exciples, as evidenced by the excerptional behavior of p-diacylbenzenes, which give the highest ratio of tertiary radicals from cymene.There is no set intrinsic ratio of reactivity for ?,?* triplets vs. n,?* triplets in these CT reactions.The two types of triplets show similar reactivity for the more easily reduced triplets, with the harder to reduce ?,?* triplets being only one-tenth as reactive as n,?* triplets of comparable triplet reduction potential.When the extent of electron transfer in the exciplex is small, hydogen transfer is rate determining and ?,?* reactivity drops.A study of two radical reactions which generate benzyl and α-hydroxy-α-methylbenzyl radicals indicates that radical disproportionation cannot explain the low quantum yields (0.10) of most ketone-toluene photoreductions, which apparently involve substantial radiation less decay by the exciplex intermediates.
- Wagner, Peter J.,Truman, Royal J.,Puchalski, Alan E.,Wake, Ronald
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p. 7727 - 7738
(2007/10/02)
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- The reduction of aryl trifluoromethyl ketones by sodium borohydride. The hydride transfer process
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The rates of reduction of 17 aryl trifluoromethyl ketones by sodium borohydride in 2-propanol have been measured.The rho (ρ) value is 3.12, excluding the 4-amino and 4-dimethylamino groups, which both lower the rate to a greater extent than their ? values predict.The close correspondence between substituent effects for hydride addition in the methyl and trifluoromethyl series (excluding the amino groups) suggests that normal substituent effects are to be expected for oxidation processes involving hydride removal in trifluoromethyl compounds.The present results are consistent with the oxidation of aryl trifluoromethyl carbi ols by permanganate taking place by hydrogen atom abstraction.The effect of substituents on the rate of reduction of the trifluoromethyl ketones is almost identical to that on the equilibrium constant for formation of the ketone hydrates.The application of the reactivity-selectivity principle to the reduction reaction is also considered.Reduction of the 4-ethyl compound has ΔH = 2.7 kcal mol-1 and ΔS = -38 cal deg-1 mol-1.
- Stewart, Ross,Teo, K. C.
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p. 2491 - 2496
(2007/10/02)
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