- 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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- 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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p. 237 - 247
(2020/02/18)
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- Photoaffinity palladium reagents for capture of protein-protein interactions
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Protein-protein interactions (PPIs) are indispensable in almost all cellular processes. Probing of complex PPIs provides new insights into the biological system of interest and paves the way for the development of therapeutics. Herein, we report a strategy for the capture of protein-protein interactions using photoaffinity palladium reagents. First, the palladium-mediated reagent site specifically transferred a photoaffinity modified aryl group to the designated cysteine residue. Next, the photoaffinity group was activated by UV radiation to trap the proximal protein residue for the formation of a crosslink. This strategy was used to capture the PYL-ABA-PP2C interaction, which is at the core of the abscisic acid (ABA) signalling pathway. Our results indicated that this palladium-mediated strategy can serve as an alternative for incorporating an increasing number of diverse substrates for protein crosslinking through cysteine modifications and can be explored for use in mapping protein-peptide or protein-protein interaction surfaces and in trapping potential interacting partners.
- Zheng, Qizhen,Pang, Zhengyuan,Liu, Jingwei,Zhou, Yi,Sun, Yang,Yin, Zheng,Lou, Zhiyong
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supporting information
p. 6369 - 6373
(2019/07/09)
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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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- 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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- Allyl m -trifluoromethyldiazirine mephobarbital: An unusually potent enantioselective and photoreactive barbiturate general anesthetic
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We synthesized 5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (14), a trifluoromethyldiazirine-containing derivative of general anesthetic mephobarbital, separated the racemic mixture into enantiomers by chiral chromatography, and determined the configuration of the (+)-enantiomer as S by X-ray crystallography. Additionally, we obtained the 3H-labeled ligand with high specific radioactivity. R-(-)-14 is an order of magnitude more potent than the most potent clinically used barbiturate, thiopental, and its general anesthetic EC50 approaches those for propofol and etomidate, whereas S-(+)-14 is 10-fold less potent. Furthermore, at concentrations close to its anesthetic potency, R-(-)-14 both potentiated GABA-induced currents and increased the affinity for the agonist muscimol in human α1β2/3γ2L GABAA receptors. Finally, R-(-)-14 was found to be an exceptionally efficient photolabeling reagent, incorporating into both α1 and β3 subunits of human α1β3 GABA A receptors. These results indicate R-(-)-14 is a functional general anesthetic that is well-suited for identifying barbiturate binding sites on Cys-loop receptors.
- Savechenkov, Pavel Y.,Zhang, Xi,Chiara, David C.,Stewart, Deirdre S.,Ge, Rile,Zhou, Xiaojuan,Raines, Douglas E.,Cohen, Jonathan B.,Forman, Stuart A.,Miller, Keith W.,Bruzik, Karol S.
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experimental part
p. 6554 - 6565
(2012/09/21)
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- 4-AMINO-5-OXO-7, 8-DIHYDROPYRIMIDO [5,4-F] [1,4] OXAZEPIN-6 (5H) -YL) PHENYL DERIVATIVES, PHARMACEUTICAL COMPOSITIONS AND USES THEREOF
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The invention provides compounds of Formula (I), wherein R1, R2a, R2b, R3, m and A are as defined herein, as well as compositions thereof and methods for treating a disease, condition or disorder that is modulated by the inhibition of the diacylglycerol O-acyltransferase 1 (DGAT-1) enzyme by administering the compounds of the present invention and/or compositions thereof.
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Page/Page column 46
(2010/08/09)
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- 4-AMINO-7,8-DIHYDROPYRIDO[4,3-d]PYRIMIDIN-5(6H)-ONE DERIVATIVES
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The invention provides compounds of the general Formula (I) where R1, R2, and A are defined herein, as well as the preparation, compositions and uses thereof.
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Page/Page column 21
(2010/08/08)
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- Stereospecific synthesis of a carbene-generating angiotensin II analogue for comparative photoaffinity labeling: Improved incorporation and absence of methionine selectivity
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A stereospecific convergent synthesis of N-[(9-fluorenyl)methoxycarbonyl]- p-[3-(trifluoromethyl)-3H-diazirin-3-yl]-L-phenylalanine (Fmoc-12, Fmoc-Tdf) and its incorporation into the C-terminal position of the angiotensin II (AngII) peptide to form 125I[Sar1,Tdf8]AngII ( 125I-13) is presented. This amino acid photoprobe is a highly reactive carbene-generating diazirine phenylalanine derivative that can be used for photoaffinity labeling. Using model receptors, we compared the reactivity and the Met selectivity of 12 to that of the widely used and reputedly Met-selectivep-benzoyl-L-phenylalanine (Bpa) photoprobe. Wild-type and mutant AngII type 2 receptors, a G protein-coupled receptors, were photolabeled with 125I-13 as well as with 125I-[Sar1,Bpa 8]AngII (125I-14), and the respective incorporation yields were assessed. The carbene-generating 12 was more reactive toward inert residues and was not Met-selective compared to the biradical ketone-generating Bpa, allowing for more precise determination of ligand contact points in peptidergic receptors.
- Pillion, Dany,Dera?t, Maud,Holleran, Brian J.,Escher, Emanuel
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p. 2200 - 2209
(2007/10/03)
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- Synthesis of a new photo-cross-linking nucleoside analogue containing an aryl(trifluoromethyl)diazirine group: Application for EcoRII and MvaI restriction-modification enzymes
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A new photo-cross-linking dU analog, 5-[4-(3-(trifluoromethyl)-3H- diazirin-3-yl)phenyl]-2'-deoxyuridine, was synthesized and incorporated into the recognition site of EcoRII and MvaI restriction-modification enzymes. The resulting base-modified 14-mer su
- Topin, Andrey N.,Gritsenko, Oxana M.,Brevnov, Maxim G.,Gromova, Elisaveta S.,Korshunova, Galina A.
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p. 1163 - 1175
(2007/10/03)
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