- New approach to a novel axially chiral ligand showing spontaneous enrichment of axial chirality.
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We have synthesized novel axially chiral ligand with two chiral centers, (R)-(R)(2)- and (S)-(S)(2)-2,2'-bis(2,2,2-trifluoro-1-hydroxyethyl)biphenyl (1), which showed a high asymmetric induction when used as ligand. Here, another new approach to 1 by kine
- Hasegawa, Tomokuni,Omote, Masaaki,Sato, Kazuyuki,Ando, Akira,Kumadaki, Itsumaro
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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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- 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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- Palladium-Catalyzed Trimethylenemethane Cycloaddition of Olefins Activated by the δ-Electron-Withdrawing Trifluoromethyl Group
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α-Trifluoromethyl-styrenes, trifluoromethyl-enynes, and dienes undergo palladium-catalyzed trimethylenemethane cycloadditions under mild reaction conditions. The trifluoromethyl group serves as a unique δ-electron-withdrawing group for the activation of the olefin toward the cycloaddition. This method allows for the formation of exomethylene cyclopentanes bearing a quaternary center substituted by the trifluoromethyl group, compounds of interest for the pharmaceutical, agrochemical, and materials industries. In the diene series, the cycloaddition operates in a [3 + 4] and/or [3 + 2] manner to give rise to seven- and/or five-membered rings. This transformation greatly improves the scope of the TMM cycloaddition technology and provides invaluable insights into the reaction mechanism.
- Trost, Barry M.,Debien, Laurent
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p. 11606 - 11609
(2015/09/28)
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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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- 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 novel axially dissymmetric ligand with chiral 2,2,2-trifluoro-1- hydroxyethyl groups
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Novel axially dissymmetric ligands (1) with two more chiral carbons were synthesized through homo-coupling of o-bromo-(R or S)-(2,2,2-trifluoro-1- acetoxyethyl)benzene. A high asymmetric induction was accomplished using 5 mol% of the Ti complex of this li
- Omote, Masaaki,Kominato, Akane,Sugawara, Michi,Sato, Kazuyuki,Ando, Akira,Kumadaki, Itsumaro
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p. 5583 - 5585
(2007/10/03)
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