- 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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- Novel Friedel-Crafts reaction method and catalyst thereof
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The present invention relates to a novel method for preparing or synthesizing an acylated or alkylated aryl compound, such as acylated or alkylated benzene, through a reaction called Friedel-Crafts, and a novel catalyst for the method. The present invention particularly relates to a novel environment-friendly method for synthesizing the Friedel-Crafts reaction of the acylated or alkylated compound.
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Paragraph 0201; 0204
(2020/02/29)
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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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p. 11017 - 11020
(2018/10/08)
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- Method for preparing 4-chloro-2-(trifluoroacetyl)aniline hydrochloride hydrate and free alkalis thereof
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The invention discloses a method for preparing a 4-chloro-2-(trifluoroacetyl)aniline hydrochloride hydrate and free alkalis thereof. The method comprises the steps: (1) subjecting an intermediate, which is obtained through subjecting a compound with a structure represented by a formula IV shown in the description to a reaction, to a reaction with trifluoroacetate or a compound with a structure represented by a formula V or a formula VI shown in the description, and then, carrying out acid treatment, so as to obtain a compound with a structure represented by a formula I shown in the description; (2) subjecting the compound with the structure represented by the formula I to a nitration reaction under the catalysis of an acid, so as to obtain a compound with a structure represented by a formula II shown in the description; and (3) subjecting the compound with the structure represented by the formula II to nitro-to-amino reduction, thereby obtaining a compound with a structure represented by a formula III shown in the description.
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Paragraph 0117; 0118; 0119; 0120
(2017/04/28)
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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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- 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 new entry for the oxidation of fluoroalkyl-substituted methanol derivatives: Scope and limitation of the organoiodine(V) reagent-catalyzed oxidation
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Oxidation of various fluoroalkyl-substituted methanol derivatives under the influence of a catalytic amount of sodium 2-iodobenzenesulfonate and Oxone in CH3CN or CH3NO2 was investigated in detail. The efficiency of the newly developed oxidation was also evaluated by comparison to other oxidations, such as Dess-Martin, PDC, and Swern oxidation.
- Tanaka, Yusuke,Ishihara, Takashi,Konno, Tsutomu
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experimental part
p. 99 - 104
(2012/05/07)
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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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- Substituent Effects on the Solvolysis of 2,2,2-Trifluoro-1,1-diphenylethyl Tosylates. II. 3-Chlorophenyl- and 3,5-Dichlorophenyl-Fixed Systems
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The solvolysis rates of 2,2,2-trifluoro-1-(3-chlorophenyl)-l-(substituted phenyl)ethyl and 2,2,2-trifluoro-1-(3,5-dichlorophenyl)-1-(substituted phenyl)ethyl tosylates or bromides were conductimetrically measured at 25.0°C in 80% aqueous ethanol. The 3-chlorophenyl-fixed series showed a bilinear Yukawa-Tsuno correlation with ρ = -4.81 and r = 1.41 for substituents more deactivating than 3,5-dimethyl, and with ρ = -6.19 and r = 1.57 for the substituent range more activating than 4-methyl. The bilinear correlation was interpreted in terms of the changing coplanarity of the two aryl rings. The 3,5-dichlorophenyl-fixed substrates gave an excellent linear Yukawa-Tsuno correlation for the substituents ranging from 4-MeO to 4-Cl with ρ = -5.95 and r = 1.69. The variable aryl rings in this series show the largest extent of resonance interaction with the extraordinary deactivated carbenium ion center by α-CF3 and α-(3,5-dichlorophenyl) groups in the transition state. The optimization of the geometries of 2,2,2-trifluoro-1,1-diphenylethyl cation and some ring-substituted derivatives was performed at the RHF/6-31G* level. The symmetric diaryl cations have equivalently twisted conformations while in unsymmetric ones the more stabilizing aryl group is less twisted from the plane of the positive sp2 carbon. The observed variation of r and ρ parameters is accommodated by geometrical changes of the incipient cation.
- Fujio, Mizue,Morimoto, Hiroshi,Kim, Hyun-Joong,Tsuno, Yuho
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p. 3081 - 3090
(2007/10/03)
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- MECHANISMS OF FREE-RADICAL REACTIONS. XIII. MECHANISM AND SELECTIVITY OF THE FREE-RADICAL HALOGENATION OF ALKYL AROMATIC HYDROCARBONS WITH FLUOROALKYL SUBSTITUENTS
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The free-radical chlorination and bromination of 1-fluoro-2-arylethanes and 1,1,1-trifluoro-2-arylethanes was studied by the method of competing reactions.In all cases a good correalation between log krel and the Brown ?+ constants was observed.The variation of the selectivity in the transition from one reaction series to the other indicates that two independent factors which determine the reactivity (the change in the dissociation energy of the C-H bond and the polar effect of the substituents) have a simultaneous effect.
- Dneprovskii, A. S.,Eliseenkov, E. V.,Mil'tsov, S. A.
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p. 317 - 324
(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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- The reduction of aryl trifluoromethyl ketones by N-carbamoylmethyl-1,4-dihydronicotinamide
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The reaction of 15 aryl trifluoromethyl ketones with N-carbamoylmethyl-1,4-dihydronicotinamide has been studied in aqueous sulfolane buffer.The unsubstituted ketone and those containing electron-withdrawing groups in the ring have the following reaction characteristics: (a) a high yield of alcohol is obtained, (b) the observed reaction rate is independent of ring substituent; however, when corrections are made for degree of hydration of the ketones the rate is correlated with Hammett ? values with a rho of 1.98, (c) a secondary isotope effect of approximately 1.08 and primary isotope effects of 1.45-1.62 are observed at 43.4 deg C for the reaction of the dihydronicotinamide containing one or two atoms of deuterium at C-4, (d) ΔH = 15.2 kcal mol-1, and ΔS = -27.0 cal deg-1 mol-1 for the unsubstituted compound, uncorrected for ketone hydration; ΔS for reaction of the unhydrated ketone and dihydronicotinamide is estimated to be -45 to -50 cal deg-1 mol-1.The mechanism for the reduction is consistent with hydride transfer from reductant to oxidant, very possibly accompanied by blind-alley formation of an adduct between ketone hydrate and dihydronicotinamide.Ketones containing electron-donating groups in the ring react with the dihydronicotinamide in some undetermined way, giving little or no alcohol as product.
- Stewart, Ross,Teo, K. C.,Ng, L. K.
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p. 2497 - 2503
(2007/10/02)
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