- Highly selective trifluoroacetic ester/ketone metathesis: An efficient approach to trifluoromethyl ketones and esters
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A highly selective and atom efficient 'trifluoroacetic ester/ketone metathesis' has been sincerely witnessed. Enolizable alkyl (at least two non-hydrogen atoms) aryl ketones were found to react readily with ethyl trifluoroacetate under the promotion of NaH to afford trifluoroacetic ester/ketone exchange products, trifluoromethyl ketones (TFMKs), and aromatic acid esters, which were quite different from the general Claisen condensation products, 1,3-diketones. The outcome of the reaction between ketone and ethyl trifluoroacetate is strongly related to the structures of substrates, the steric congestion caused by alkyl group is in favor of the C-C bond cleavage. DFT investigation further disclosed that the metathesis reaction was a kinetically favored pathway. Using only a slight excess of cheap trifluoromethylation reagent, simple operation and mild conditions make it a practical method for preparation of TFMKs on large scale, as well as a new choice of converting aryl alkyl ketones to aromatic acid esters.
- Zhou, Yuhan,Yang, Dongmei,Luo, Gen,Zhao, Yilong,Luo, Yi,Xue, Na,Qu, Jingping
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p. 4668 - 4674
(2014/06/23)
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- Exploiting the facile release of trifluoroacetate for the α-methylenation of the sterically hindered carbonyl groups on (+)-sclareolide and (-)-eburnamonine
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An efficient method for the α-methylenation of carbonyl groups is reported, and this transformation is accomplished by a facile elimination of trifluoroacetate during the formation of the olefin. This method represents an improvement beyond existing protocol in cases of steric hindrance, and we have demonstrated the utility of the process across a series of ketones, lactams, and lactones. Additionally, we have applied this method to produce semisynthetic derivatives of the natural products (+)-sclareolide and (-)-eburnamonine, in which the carbonyl group is proximal to bulky functional groups. Mechanistic insight is also provided from a time course of 19F NMR. Biological evaluation of the natural-product-derived enones led to the identification of a derivative of (-)-eburnamonine with significant cytotoxicity (LC50 = 14.12 ?M) in drug-resistant MDA-MB-231 breast cancer cells.
- Riofski, Mark V.,John, Jinu P.,Zheng, Mary M.,Kirshner, Julia,Colby, David A.
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experimental part
p. 3676 - 3683
(2011/06/24)
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- Discovery of a potent, selective and orally active canine COX-2 inhibitor, 2-(3-difluoromethyl-5-phenyl-pyrazol-1-yl)-5-methanesulfonyl-pyridine
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Structure-activity relationship (SAR) studies of 2-[3-di(and tri)fluoromethyl-5-arylpyrazol-1-yl]-5-methanesulfonylpyridine derivatives for canine COX enzymes are described. This led to the identification of 12a as a lead candidate for further progression. The in vitro and in vivo activity of 12a for the canine COX-2 enzyme as well as its in vivo efficacy and pharmacokinetic properties in dog are highlighted.
- Li, Jin,Lundy DeMello, Kristin M.,Cheng, Henry,Sakya, Subas M.,Bronk, Brian S.,Rafka, Robert J.,Jaynes, Burton H.,Ziegler, Carl B.,Kilroy, Carolyn,Mann, Donald W.,Nimz, Eric L.,Lynch, Michael P.,Haven, Michelle L.,Kolosko, Nicole L.,Minich, Martha L.,Li, Chao,Dutra, Jason K.,Rast, Bryson,Crosson, Rhonda M.,Morton, Barry J.,Kirk, Glen W.,Callaghan, Kathleen M.,Koss, David A.,Shavnya, Andrei,Lund, Lisa A.,Seibel, Scott B.,Petras, Carol F.,Silvia, Annette
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- Substituted pyrazolyl benzenesulfonamides for use in veterinary therapies
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A method of using pyrazolyl benzenesulfonamide compounds in treating inflammation and inflammation-related disorders in companion animals is disclosed.
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- Substituted pyrazolyl benzenesulfonamides for the treatment of inflammation
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A class of pyrazolyl benzenesulfonamide compounds is described for use in treating inflammation and inflammation-related disorders. Compounds of particular interest are defined by Formula II: STR1 or a pharmaceutically-acceptable salt thereof.
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- 4-Dimethylamino-1-trifluoroacetylpyridinium trifluoroacetate: An efficient reagent for the preparation of trifluoromethyl 1,3-dicarbonyl compounds
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Enamines 2 and O-trimethylsilyl ketene acetals 4 are trifluoroacetylated on reaction with the title reagent to yield trifluoroacetyl enamines 3 and trifluoromethylsilylenol ethers 5, respectively. Trifluoromethyl 1,3-diketones 6 and trifluoromethyl β-keto esters 7 are obtained by hydrolysis of compounds 3 and 5.
- Simchen, Gerhard,Schmidt, Andreas
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p. 117 - 120
(2007/10/03)
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- α-Substituted β-diketones: Effect of the α substituent on the complexation and selectivity for lanthanides
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Some β-diketones having a substituent at the α position have been prepared and their keto-enol tautomerism, acid dissociation reaction and complexation with lanthanides have been studied. The tautomerism was examined by 1H NMR spectroscopy, rev
- Le, Quyen T. H.,Umetani, Shigeo,Suzuki, Mitsuko,Matsui, Masakazu
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p. 643 - 647
(2007/10/03)
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