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Pashkevich, K. I.; Sevenard, Dmitri V.; Khomutov, O. G.; Vorontsov, Ivan I.

doi:10.1023/a:1011317013265

Cited by 11 publications

(13 citation statements)

References 9 publications

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“…phase dried (MgSO 4 ) and evaporated, and the residue purified by CC (CHCl 3 ). The yellow oil obtained after evaporation of the single fraction was a mixture of several CF 3 -containing compounds according to the 19 Reaction of (2E)-2-Benzylidene-5-(trifluoroacetyl)cyclopentanone (3d) with Hydroxylamine. To a soln.…”

Section: Experimental Partmentioning

confidence: 99%

See 1 more Smart Citation

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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Section: Experimental Partmentioning

confidence: 99%

“…In this case, the reaction afforded a complex mixture of several compounds (according to 19 F-NMR data). The MS of this mixture shows a set of signals that could be ascribed to a possible 1 : 1 adduct of 1h and hydroxylamine (m/z 195 (60, M ), 178 (30, [M À OH] ), 108 (100, [M À H 2 O À CF 3 ] ).…”

mentioning

confidence: 99%

Reaction of 2-(Polyfluoroacyl)cycloalkanones with Hydroxylamine

Sevenard¹,

Khomutov²,

Pashkevich³

et al. 2002

HCA

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show abstract

“…catalysis for 4 to 26 h, 12 we have obtained products 6-(2-heteroaryl)-2-methyl-4-trifluoromethyl-pyrimidines 3a and 3b in good yields using alkaline medium, reacting acetamidine hydrochloride with a 1 mol L -1 KOH aqueous solution and adding to MeOH solution of 1a or 1b at room temperature. TLC analyses during reaction period have revealed that the 1,3-dielectrophiles were consumed after 1 hour, furnishing good yields of the pyrimidines 3.…”

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confidence: 95%

“…12 The 1 H NMR spectra have show a single set of signals (see, Experimental) indicating that compounds 2a and 2b exist as one of the possible tautomers. The 2(1H)pyrimidin-2-one structure was confirmed by characteristic signal from N-H at 12.93-12.95 ppm.…”

mentioning

confidence: 96%