Reaction of N-aryl-3-oxobutanethioamides with 2-amino-1,3-thiazole and 2-amino-1,3-benzothiazole

Britsun, V. N.; Borisevich, A. N.; Esipenko, A. N.; Lozinskii, M. O.

doi:10.1134/s1070428007010137

“…Whilst the reactions of 3-oxopropanethioamides with 1,2-dinucleophiles and 1,2-and 1,3-dielectrophilic reagents were investigated earlier, recently it was shown that they can also react with nitrogen-containing 1,3-dinucleophiles of heterocyclic [71,[76][77][78][79] and acyclic [80] structures.…”

Section: [3+3] Cyclocondensation Of 3-oxopropanethioamides With 13-dmentioning

confidence: 99%

Heterocyclization of thioamides containing an active methylene group (review)

Britsun

¹

,

Esipenko

²

,

Lozinskii

³

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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“…Such a course should prove an addition to the general results of preceding work [1][2][3][4], in particular the observation of the effect of the nucleophilicity of the 2-aminoazole and the acidity of the solvent on the regioselectivity of the process.Since the [3+3] cyclocondensation can occur at three reaction centers in the N-aryl-3-oxobutanethioamides 1a-d and at two in the 5-amino-3-R-4-R 1 -pyrazoles 2a-c the reaction products can be four groups of compounds i.e. 2(4)-methyl-7-R-8-R 1 -1,4(1,2)-dihydropyrazolo[1,5-a]pyrimidine-4(2)-thiones and 4(2)-arylamino-2(4)-methyl-7-R-8-R 1 -pyrazolo[1,5-a]pyrimidines.…”

mentioning

confidence: 89%

“…Such a course should prove an addition to the general results of preceding work [1][2][3][4], in particular the observation of the effect of the nucleophilicity of the 2-aminoazole and the acidity of the solvent on the regioselectivity of the process.…”

mentioning

confidence: 89%

“…

We have recently shown that N-aryl-3-oxobutanethioamides react with such 2-aminoazoles (azines) as 3-amino-5-R-1,2,4-triazoles [1], 2-amino-5-R-pyridines [2], 2-amino-4-R-5-R 1 -thiazoles [3], and 5-aminotetrazole [4] via a [3+3] cycloaddition scheme to form two groups of compounds (pyrimidine-4-thione and 4-(arylamino)pyrimidine derivatives) the ratio of which depends on the basicity of the heterocyclic 1,3-dinucleopile and the acidity of the solvent [1][2][3][4].The aim of this work is to continue our investigation [1-4] and study of the regioselectivity of the cyclization of the N-aryl-3-oxobutanethioamides 1a-d with such 1,3-dinucleophiles as the 5-amino-3-R-4-R 1 -pyrazoles, viz 5-amino-3-methylpyrazole (2a), 5-amino-4-cyanopyrazole (2b), and 3-amino-2H-pyrazolo-[3,4-b]pyridine (2c) in the absence and the presence of a proton donor solvent. Such a course should prove an addition to the general results of preceding work [1][2][3][4], in particular the observation of the effect of the nucleophilicity of the 2-aminoazole and the acidity of the solvent on the regioselectivity of the process.

Since the [3+3] cyclocondensation can occur at three reaction centers in the N-aryl-3-oxobutanethioamides 1a-d and at two in the 5-amino-3-R-4-R 1 -pyrazoles 2a-c the reaction products can be four groups of compounds i.e.

…”

mentioning

confidence: 99%

“…We have recently shown that N-aryl-3-oxobutanethioamides react with such 2-aminoazoles (azines) as 3-amino-5-R-1,2,4-triazoles [1], 2-amino-5-R-pyridines [2], 2-amino-4-R-5-R 1 -thiazoles [3], and 5-aminotetrazole [4] via a [3+3] cycloaddition scheme to form two groups of compounds (pyrimidine-4-thione and 4-(arylamino)pyrimidine derivatives) the ratio of which depends on the basicity of the heterocyclic 1,3-dinucleopile and the acidity of the solvent [1][2][3][4].…”

mentioning

confidence: 99%

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Cyclocondensation of N-aryl-3-oxobutanethioamides with 5-amino-3-R-4-R1-pyrazoles

Britsun

¹

2008

Chem Heterocycl Comp

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We have recently shown that N-aryl-3-oxobutanethioamides react with such 2-aminoazoles (azines) as 3-amino-5-R-1,2,4-triazoles [1], 2-amino-5-R-pyridines [2], 2-amino-4-R-5-R 1 -thiazoles [3], and 5-aminotetrazole [4] via a [3+3] cycloaddition scheme to form two groups of compounds (pyrimidine-4-thione and 4-(arylamino)pyrimidine derivatives) the ratio of which depends on the basicity of the heterocyclic 1,3-dinucleopile and the acidity of the solvent [1][2][3][4].The aim of this work is to continue our investigation [1-4] and study of the regioselectivity of the cyclization of the N-aryl-3-oxobutanethioamides 1a-d with such 1,3-dinucleophiles as the 5-amino-3-R-4-R 1 -pyrazoles, viz 5-amino-3-methylpyrazole (2a), 5-amino-4-cyanopyrazole (2b), and 3-amino-2H-pyrazolo-[3,4-b]pyridine (2c) in the absence and the presence of a proton donor solvent. Such a course should prove an addition to the general results of preceding work [1][2][3][4], in particular the observation of the effect of the nucleophilicity of the 2-aminoazole and the acidity of the solvent on the regioselectivity of the process.Since the [3+3] cyclocondensation can occur at three reaction centers in the N-aryl-3-oxobutanethioamides 1a-d and at two in the 5-amino-3-R-4-R 1 -pyrazoles 2a-c the reaction products can be four groups of compounds i.e. 2(4)-methyl-7-R-8-R 1 -1,4(1,2)-dihydropyrazolo[1,5-a]pyrimidine-4(2)-thiones and 4(2)-arylamino-2(4)-methyl-7-R-8-R 1 -pyrazolo[1,5-a]pyrimidines.It was shown that two groups of compounds are the result of the reaction, i.e. the pyrimidine thiones 3a,b and the 4-(arylamino)pyrazolo[1,5-a]pyrimidines 4a-f. The structure of the dihydropyrazolo[1,5-a]pyrimidine thiones 3a,b was proved by thionation of the 2,7-dimethyl-1,4-dihydropyrazolo-[1,5-a]pyrimidin-4-one 5 (the structure of which had been proved using X-ray analysis [5]) to give the 2,7-dimethyl-1,4-dihydropyrazolo-[1,5-a]pyrimidine-4-thione (3a). Since the 5-amino-3-R-4-R 1 -pyrazoles are isoelectronic with 3-amino-__________________________________________________________________________________________

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