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Sevenard, Dmitri V.; Khomutov, O. G.; Кодесс, М. И.; Pashkevich, K. I.; Loop, Ildiko; Lork, Enno; Roeschenthaler, Gerd‐Volker

doi:10.1071/ch01027

Cited by 15 publications

(11 citation statements)

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“…While the reaction of 1,3-diketone 1b in the presence of catalytic amounts of BF 3 · Et 2 O delivered the aryli- Scheme 4. dene derivative 7 in 61 % yield [12], a mixture was obtained in the case of 3, where both starting compounds (even after the reaction being maintained for 78 h), 1b and 1,3,2-dioxaborine 8 (an insignificant amount) could be identified by 1 H and 19 F NMR spectroscopy. This fact indicates clearly that the Lewis acid activates the aldehyde toward nucleophilic attack of 1, and that the formation of a boron chelate of type 3 is not a crucial step of the reaction.…”

Section: Resultsmentioning

confidence: 99%

“…Cyclocondensation of 1,3-diketones with hydrazines is a conventional synthetic route to pyrazoles, e. g., in the case 1b the pyrazole 4h is formed in less than 50 % overall yield (referring to the starting cyclohexanone [11,22]). Use of sodium salt 2h allowed us to obtain compound 4h in 70 % overall yield in a very simple two-step reaction sequence (Scheme 3).…”

Section: Resultsmentioning

confidence: 99%

“…In order to elucidate the role of BF 3 · Et 2 O in the course of the condensation of 1,3-diketones 1 with (het)aromatic aldehydes [12], we have studied the reaction of boron chelate 3 with anisaldehyde (Scheme 4). While the reaction of 1,3-diketone 1b in the presence of catalytic amounts of BF 3 · Et 2 O delivered the aryli- Scheme 4. dene derivative 7 in 61 % yield [12], a mixture was obtained in the case of 3, where both starting compounds (even after the reaction being maintained for 78 h), 1b and 1,3,2-dioxaborine 8 (an insignificant amount) could be identified by 1 H and 19 F NMR spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

“…The white precipitate was filtered off, washed with water (15 mL) and air-dried to afford 3.0 g (ca. 100 %) of analytically pure pyrazole 4h [11].…”

Section: 567-tetrahydro-3-trifluoromethyl-1h-indazole (4h)mentioning

confidence: 99%

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Metal and Boron Derivatives of Fluorinated Cyclic 1,3-Dicarbonyl Compounds

Sevenard

Khomutov

Boltachova

et al. 2009

Zeitschrift Für Naturforschung B

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Starting from the corresponding cyclic 1,3-diketones or other precursors (cyclic ketones as well as lactones), several new salts and chelate complexes of fluorinated 1,3-dicarbonyls were obtained. Their preparative significance was demonstrated by straightforward syntheses of fluorinated pyrazoles, benzimidazoles and 1,7-ketoesters. The structure of a boron chelate of 2-(trifluoroacetyl)-cyclohexanone was investigated by X-ray diffraction.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The white precipitate was filtered off, washed with water (15 mL) and air-dried to afford 3.0 g (ca. 100 %) of analytically pure pyrazole 4h [11].…”

Section: 567-tetrahydro-3-trifluoromethyl-1h-indazole (4h)mentioning

confidence: 99%

See 2 more Smart Citations

Metal and Boron Derivatives of Fluorinated Cyclic 1,3-Dicarbonyl Compounds

Sevenard

Khomutov

Boltachova

et al. 2009

Zeitschrift Für Naturforschung B

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“…[1][2][3][4][5][6] The keto-enol and enol-enol tautomerism has been extensively studied in the perfluoroalkyl substituted 1,3-dicarbonyl compounds. 7,8 Thus 2-perfluoroacylcycloalkanones are important molecules, which offer a variety of pathways in inorganic and organic synthesis, as all the perfluoroalkyl substituted 1,3-dicarbonyl compounds these are versatiles building blocks for regiospecific heterocyclic synthesis and have high affinity for diverse metallic cations in coordination chemistry.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of the omega-brominated alpha-trifluoroacetylcycloalkanones and their isoxazole derivatives

Flores¹,

Peres²,

Piovesan³

et al. 2006

J. Braz. Chem. Soc.

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Reaction of 2-(Polyfluoroacyl)cycloalkanones with Hydroxylamine

Sevenard¹,

Khomutov²,

Pashkevich³

et al. 2002

HCA

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The 2-acylcycloalkanones 1a ± g and 3a ± c, possessing a polyfluoroalkyl group, react with hydroxylamine regio-and stereoselectively to yield 4,5-dihydroisoxazol-5-ols 2a ± g and 4a ± c, respectively, i.e., products of Naddition to the oxo group at the cycloalkane ring (Schemes 1 and 2). The products 2 and 4 can be dehydrated under drastic conditions only (Schemes 3 and 4). The structure of one of the 4,5-dihydroisoxazol-5-ols was confirmed by X-ray crystal-structure analysis.Introduction. ± The interaction of 1,3-dicarbonyl compounds with hydroxylamine is considered to be one of the basic synthetic routes to isoxazole derivatives [1], which possess significant chemical potential [1] [2], as well as various biological activities [3].For a nonsymmetrical 1,3-dicarbonyl substrate in this reaction, the formation of regioisomers is possible. Thus, in the case of 2-acetylcyclohexanone, a mixture of isomeric 3-methyl-and 5-methylisoxazoles was obtained [4] [5]. The introduction of a polyfluorinated substituent in the 1,3-dicarbonyl compound results in a significant change of the electron-density distribution and consequently in a change of relative reactivity of the two carbonyl groups. The reaction of linear polyfluoroalkyl 1,3-diketones with hydroxylamine occurs unambigously affording 4,5-dihydro-5-(polyfluoroalkyl)isoxazol-5-ols exclusively ± an intermediate step in the 5-(polyfluoroalkyl)isoxazole formation. The dihydroisoxazolols represent stable compounds that may be dehydrated to the corresponding isoxazoles under drastic conditions only [6 ± 8]. Moreover, 2-(trifluoroacetyl)-and 2-(polychloroacetyl)-substituted cyclohexanones [5], triterpen-3-ones [9], and homoadamantanone [10] are known to give 4,5-dihydro-5-R Hal -isoxazol-5-ols, 5-(trifluoromethyl)isoxazoles, or 3-(trifluoromethyl)isoxazoles in the reaction with hydroxylamine, depending on the size of the carbocyclic ring in the 1,3-diketone molecule and on the reaction conditions.Among the 2-acyl-substituted cycloalkanones, the cyclopentanone derivatives represent a special case, forming an alternative product ± 4,5-dihydro-3-R-isoxazol-5-ols ± in the reaction with hydroxylamine, independent of the presence of F-atoms in the RCO moiety [11]. In the case of 2-(trifluoroacetyl)cyclopentanone, the dioxime [11], which cyclizes in acidic medium only, was also isolated.The present work aimed at the investigation of the chemical behavior of a variety of 2-(polyfluoroacyl)cycloalkanones in the reaction with hydroxylamine, the former differing in ring size, (polyfluoroalkyl)-radical length, and the presence of substituents at the cycloalkane ring. The expected products of such reactions can possess a set of

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Cited by 15 publications

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Metal and Boron Derivatives of Fluorinated Cyclic 1,3-Dicarbonyl Compounds

Metal and Boron Derivatives of Fluorinated Cyclic 1,3-Dicarbonyl Compounds

Synthesis of the omega-brominated alpha-trifluoroacetylcycloalkanones and their isoxazole derivatives

Reaction of 2-(Polyfluoroacyl)cycloalkanones with Hydroxylamine

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