Conditions for the Selective Conversion of Quaternary 3-Anilino-1,5-dimethylpyrazolium Salts into 3-Anilino-1,5-dimethylpyrazole

Dzvinchuk, I. B.; Kartashov, S. A.; Vypirailenko, A. V.; Döller, Uwe; Lozinskii, M. O.

doi:10.1023/b:cohc.0000037311.01960.3e

Cited by 4 publications

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“…During pyrolysis of the latter 1,3-dimethyl-5-phenylaminopyrazole 138 and 1,5-dimethyl-3-phenylaminopyrazole 140 are formed in a approximately equal ratio. At the same time the betaine 4-(1,2,5-trimethylpyrazol-3-ylamino)benzenesulfonate 142 was unexpectedly obtained during the methylation of 1-benzoylpyrazole 141 with dimethyl sulfate [75]. In the end by improving the method of decomposition of the pyrazolium salts 143 it was possible to develop a chemoselective method for the synthesis of previously unknown 3-arylamino-1,5-dimethylpyrazoles 140 [75].…”

Section: [3+2] Cyclization Of 3-oxopropanethioamides With 12-dinuclementioning

confidence: 99%

Heterocyclization of thioamides containing an active methylene group (review)

Britsun

Esipenko

Lozinskii

2008

Chem Heterocycl Comp

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Data from the last six years on the heterocyclization of thioamides containing an active methylene group are analyzed and classified.At the present time there has been a considerable increase in the number of publications on the chemistry of thioamides, and this is explained by the value of the compounds as initial reagents for further transformations and particularly for the synthesis of various sulfur-and nitrogen-containing heterocycles [1][2][3][4][5][6][7][8]. The enormous practical significant of the latter is common knowledge -they have found application as drugs, pesticides, dyes, and preservatives.Thioamides with an active methylene group are attractive synthesis units for the production of heterocycles. These polyfunctional compounds can be represented by the formula R 3 -CH 2 CS-NR 1 R 2 (where R 1 , R 2 = H, Alk, Ar; R 3 is an electron-withdrawing group such as CN, AlkCO, ArCO, (AlkO) 2 PO, AlkSO 2 , ArSO 2 , NO 2 ). The presence of another reaction center (the methylene group) makes it possible to use them as N-С-С and S-C-C components for various condensations [1][2][3][4][5][6][7][8]. A special feature of such substrates is the ability to react both with dinucleophilic and with dielectrophilic and dipolar reagents. As a rule the products of these heterocyclizations contain functional groups, which makes it possible to achieve their modification or annelation. Such characteristics of thioamides with an active methylene group substantially increase their synthetic potential and extend the range of accessible heterosystems, while the use of modern physical methods of investigation (X-ray crystallographic analysis and 1D and 2D NMR spectroscopy) makes it possible to establish the structure of the obtained compounds unambiguously. The presence of biological activity in the products of these transformations also attracts investigators to this subject [5][6][7][8].The reason for the appearance of this review was the increasing need for generalization and classification of new information on the heterocyclization of such thioamides that had not been included in previous reviews [2][3][4][5] and also to define the trends in the study of these processes. Since one of the most important reports in this field is the review [1] we undertook an analysis of the literature that has appeared in the last six years.

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Section: [3+2] Cyclization Of 3-oxopropanethioamides With 12-dinuclementioning

confidence: 99%

Heterocyclization of thioamides containing an active methylene group (review)

Britsun

Esipenko

Lozinskii

2008

Chem Heterocycl Comp

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“…Unlike 5-arylamino-1,3-disubstituted pyrazoles [8,9], the 1,5-dialkyl-3-arylaminopyrazoles are less accessible [10].…”

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Heterocyclization of 3-(R-amino)-3-methylthio-1-phenylpropenones and 5-benzoyl-6-methylthio-1,2-dihydropyridin-2-ones with 1,2- and 1,3-dinucleophilic reagents

Britsun

Pikun

Ryabitskii

et al. 2011

Chem Heterocycl Comp

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Keywords: 1-alkyl-5-benzoyl-3-ethoxycarbonyl-6-methylthio-1,2-dihydropyridin-2-ones, 6-amino-5-benzoyl-3-ethoxycarbonyl-1-methyl-1,2-dihydropyridin-2-one, 3-(R-amino)-3-methylthio-1-phenylpropenones, 1-R 1 -5-(R-amino)-3-phenylpyrazoles, benzimidazo[1,2-a]pyridines, benzimidazo[1,2-a]-pyrimidines, 6,7-dihydro-2H-pyrazolo [3,4-b]pyridines, 1,2,4-triazole, [1,2,4]triazolo[4,3-b]pyridazines, heterocyclization, [3+2] and [3+3] cyclocondensations.3-Alkylthio-3-(R-amino)-1-arylpropenones may react both with electrophilic and with nucleophilic and polycentered reagents. As a result of this they are desirable starting materials for the synthesis of nitrogencontaining heterocycles, derivatives of pyrimidine, pyrrole, pyridine, isoxazole, and quinoline [1][2][3][4][5]. In reactions with nucleophiles these substrates react at two reaction centers, at the carbonyl group and at C-3 [5]. The relative ease of carrying out such heterocyclizations is caused by the good nucleofugicity of the alkylthio group of 3-alkylthio-3-(R-amino)-1-aryl-propenones. In addition the presence of competing reaction centers may lead to nonselectivity in the execution of reactions of 3-alkylthio-3-(R-amino)-1-aryl-propenones with unsymmetrical dinucleophiles. It should be mentioned that, with the exception of [5], no investigations have been carried out in this area.

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