- Cycloaddition Chemistry of Tetrafluorothiophene S,S-Dioxide
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Tetrafluorothiophene S,S-dioxide has been found to be a powerful and versatile cycloaddend that undergoes a wide range of reactions as a Diels-Alder diene, dienophile, and [2 + 2] addend. Because it dimerizes only slowly at high temperatures, a broad range of conditions are available for these transformations. Reactions with terminal alkynes yield products of both Diels-Alder and [2 + 2] cycloaddition. Remarkably, the orbital topology-forbidden [2 + 2] process sometimes dominates over the allowed Diels-Alder reaction.
- Lemal, David M.
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p. 4931 - 4938
(2016/07/06)
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- Catalytic defluorination of perfluorinated aromatics under oxidative conditions using N-bridged diiron phthalocyanine
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Carbon-fluorine bonds are the strongest single bonds in organic chemistry, making activation and cleavage usually associated with organometallic and reductive approaches particularly difficult. We describe here an efficient defluorination of poly- and perfluorinated aromatics under oxidative conditions catalyzed by the μ-nitrido diiron phthalocyanine complex [(Pc)Fe III(μ-N)FeIV(Pc)] under mild conditions (hydrogen peroxide as the oxidant, near-ambient temperatures). The reaction proceeds via the formation of a high-valent diiron phthalocyanine radical cation complex with fluoride axial ligands, [(Pc)(F)FeIV(μ-N)FeIV(F) (Pc+?)], which was isolated and characterized by UV-vis, EPR, 19F NMR, Fe K-edge EXAFS, XANES, and Kβ X-ray emission spectroscopy, ESI-MS, and electrochemical techniques. A wide range of per- and polyfluorinated aromatics (21 examples), including C6F6, C6F5CF3, C6F5CN, and C6F5NO2, were defluorinated with high conversions and high turnover numbers. [(Pc)FeIII(μ-N)Fe IV(Pc)] immobilized on a carbon support showed increased catalytic activity in heterogeneous defluorination in water, providing up to 4825 C-F cleavages per catalyst molecule. The μ-nitrido diiron structure is essential for the oxidative defluorination. Intramolecular competitive reactions using C6F3Cl3 and C6F3H 3 probes indicated preferential transformation of C-F bonds with respect to C-Cl and C-H bonds. On the basis of the available data, mechanistic issues of this unusual reactivity are discussed and a tentative mechanism of defluorination under oxidative conditions is proposed.
- Colomban, Cédric,Kudrik, Evgenij V.,Afanasiev, Pavel,Sorokin, Alexander B.
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supporting information
p. 11321 - 11330
(2014/11/07)
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- Trifluoro-3-hydroxy-1H-indazolecarboxylic acids and esters from perfluorinated benzenedicarboxylic acids
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Twelve new 3-hydroxyindazoles, each bearing three fluorine substituents and a CO2R group (R = H, CH3, C2H5) distributed around its 4-, 5-, 6-, and 7-positions, have been synthesized. They were studied by NMR in
- Medina, Carlos Perez,Lopez, Concepcion,Claramunt, Rosa M.,Elguero, Jose
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scheme or table
p. 890 - 899
(2010/04/23)
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- o-fluoranil chemistry: Diels-Alder versus hetero-Diels-Alder cycloaddition
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(Chemical Equation Presented) The title quinone undergoes [4 + 2] cycloadditions in two ways, Diels-Alder on the ring and hetero-Diels-Alder by attack at the oxygens. The latter mode of reaction is strongly favored thermodynamically, but there is a kinetic bias favoring the normal Diels-Alder addition that often prevails, especially with cycloaddends that are not electron-rich.
- Lemal, David M.,Ramanathan, Sudharsanam,Shellito, John
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p. 3392 - 3396
(2008/09/21)
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- Pyridonecarboxylic acid derivatives substituted by a bicyclic amino group as antibacterials
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This invention relates to a N1 -(halogenocyclopropyl)-substituted pyridonecarboxylic acid derivative represented by the following formula (I): STR1 wherein X1 is a halogen atom or a hydrogen atom; X2 is a halogen atom; R1 is a hydrogen atom, a hydroxyl group, a thiol group, a halogenomethyl group, an amino group, an alkyl group or an alkoxy group which may have a substituent group; R2 is a group represented by the following formula (II): STR2 wherein R3 and R4 are independently a hydrogen atom or an alkyl group and n is an integer of 1 or 2; A is a nitrogen atom or a partial structure of the following formula (III): STR3 wherein X3 is a hydrogen atom, a halogen atom, a cyano group, an amino group, an alkyl group, a halogenomethyl group, an alkoxyl group or a halogenomethoxyl group which may have a substituent group; and R is a hydrogen atom, a phenyl group, an acetoxymethyl group, a pivaloyloxymethyl group, an ethoxycarbonyl group, a choline group, a dimethylaminoethyl group, a 5-indanyl group, a phthalidynyl group, a 5-alkyl-2-oxo-1,3-dioxol-4-ylmethyl group, a 3-acetoxy-2-oxobutyl group, an alkyl group, an alkoxymethyl group or a phenylalkyl group, and provides a heterocyclic compound useful as antibacterial drugs.
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- Process for the synthesis of 3-chloro-2,4,5-trifluorobenzoic acid
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An improved process for the preparation of 3-chloro-2,4,5-trifluorobenzoic acid is described which involves reaction of a diester of 3,4,5,6-tetrafluoro-1,2-benzenedicarboxylic acid with a substituted amine to afford 3-amino-2,4,5-trifluorobenzoic acid followed by subsequent conversion of the amio intermediate into 3-chloro-2,4,5-trifluorobenzoic acid.
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- Process for tetrafluorobenzoic acid
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An improved process for the preparation of 2,3,4,5-tetrafluorobenzoic acid is described which involves decarboxylation of tetrafluorophthalic acid in the presence of a base catalyst. Also described is an improved method for preparing tetrafluorophthalic acid and, in turn, a one-pot process for tetrafluorobenzoic acid using the combination of the two improvements.
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