Ring-chain tautomerism of the condensation product of acetone with 2-sulfanylbenzohydrazide

Еrshov, A. Yu.; Lagoda, I. V.; Yakimovich, S. I.; Pakal’nis, V. V.; Шаманин, В. В.

doi:10.1134/s1070428007110310

Cited by 4 publications

(9 citation statements)

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“…This reaction is sometimes reversible, which leads to the coexistence of the hydrazone and cyclic forms as their tautomeric mixture in solution [3,4]. Thus, the thiosalicyloylhydrazone of acetone obtained in our laboratory transforms in solution to the alternative 1,3,4-benzothiadiazepine form [5]. We note that the hydrazones obtained using the hydrazides of salicylic and anthranilic acids have linear structure.…”

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confidence: 92%

Thiosalicyloylhydrazones of aliphatic aldehydes and their cyclization to give 1,3,4-benzothiadiazepine derivatives

Еrshov

Lagoda²,

Мокеев

et al. 2008

Chem Heterocycl Comp

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The tendency of functionally-substituted hydrazones to undergo intramolecular cyclization at the polar C=N bond of the hydrazone fragment is commonly used in the synthesis of five-and six-membered heterocycles [1,2]. This reaction is sometimes reversible, which leads to the coexistence of the hydrazone and cyclic forms as their tautomeric mixture in solution [3,4]. Thus, the thiosalicyloylhydrazone of acetone obtained in our laboratory transforms in solution to the alternative 1,3,4-benzothiadiazepine form [5]. We note that the hydrazones obtained using the hydrazides of salicylic and anthranilic acids have linear structure. The possible cyclization at the C=N bond by attack of the available OH or NH functions does not occur [6,7]. SH N NH 2 O H SH N H H N O R S N NH O H R RCH O 2a-f B E,Z'-A 1 2 a R = Me, b R = Et, c R = Pr, d R = Bu, e R = i-Pr, f R = i-Bu

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confidence: 92%

Thiosalicyloylhydrazones of aliphatic aldehydes and their cyclization to give 1,3,4-benzothiadiazepine derivatives

Еrshov

Lagoda²,

Мокеев

et al. 2008

Chem Heterocycl Comp

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“…Condensation products of 2-sulfanylbenzohydrazide with monocarbonyl compounds tend to undergo intramolecular cyclization via nucleophilic addition of the SH group at the C=N bond with formation of seven-membered benzo-1,3,4-thiadiazepine ring [1][2][3]. In some cases this process is reversible, so that equilibrium mixture of linear 2-sulfanylbenzoylhydrazone and cyclic benzothiadiazepine tautomers may exist in solution.…”

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confidence: 98%

Structure of aldose condensation products with 2-hydroxyand 2-sulfanylbenzohydrazides

et al. 2010

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The structure of the condensation products of 2-hydroxy-and 2-sulfanylbenzohydrazides with a series of aldoses (L-arabinose, D-ribose, L-ramnose, D-galactose, D-glucose, D-mannose) was studied by 1 H and 13 C NMR spectroscopy. The condensation products of monosaccharides with 2-hydroxybenzohydrazide in DMSO-d 6 solution exist as equilibrium mixtures of linear hydrazone and cyclic pyranose and furanose forms, the cyclic tautomers being represented by two stereoisomers (α-and β-anomers). The aldose condensation products with 2-sulfanylbenzohydrazide in the crystalline state have cyclic 1,3,4-benzothiadiazepine structure, while in DMSO-d 6 solution they undergo complete or partial isomerization into cyclic pyranose tautomer.Condensation products of 2-sulfanylbenzohydrazide with monocarbonyl compounds tend to undergo intramolecular cyclization via nucleophilic addition of the SH group at the C=N bond with formation of seven-membered benzo-1,3,4-thiadiazepine ring [1-3]. In some cases this process is reversible, so that equilibrium mixture of linear 2-sulfanylbenzoylhydrazone and cyclic benzothiadiazepine tautomers may exist in solution.In continuation of our previous studies [1-3], in the present work we examined the structure of the condensation products obtained from 2-hydroxy-and 2-sulfanylbenzohydrazides IIa and IIb and a series of aldoses Ia-If. Compounds IIIa-IIIl were synthesized in good yields (55-90%) by heating equimolar amounts of the corresponding monosaccharide (L-arabinose, D-ribose, L-ramnose, D-galactose, D-glucose, D-mannose) and hydrazide in boiling methanol for a short time (see Experimental).2-Hydroxy-and 2-sylfanylbenzoylhydrazones IIIaIIIl are complex tautomeric systems that are capable of existing as cyclic five-and six-membered tautomers A and C and linear hydrazone structure B. In addition, condensation products IIIg-IIIl derived from aldoses and 2-sulfanylbenzohydrazide (IIb) could give rise to seven-membered 1,3,4-benzothiadiazepine form D as a result of attack by the SH group on the C=N bond. It should be also taken into account that each cyclic form A, C, and D may be a mixture of two stereoisomers [α-and β-anomers for structures A and C and (2R)-and (2S)-stereoisomers for structure D]. The formation of analogous seven-membered cyclic 1,3,4-benzoxadiazepine tautomers for 2-hydroxybenzoylhydrazones IIIa-IIIf via attack by the OH group on the C=N bond should be ruled out. It is known that condensation products of 2-hydroxybenzohydrazide with aldehydes and ketones have exclusively linear structure and they do not tend to undergo the above cyclization [4,5].In all experiments, the 1 H and 13 C NMR spectra were recorded at definite time intervals starting from the moment of dissolution until the end of transformations. In addition, the structure of the compounds under study in the crystalline state was confirmed by solid-phase high-resolution 13 C NMR spectroscopy

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“…Hydrazones derived from 3-sulfanylpropionic acid hydrazide and aromatic aldehydes and ketones have mostly linear structures of different stereoisomers arising from Z-E isomerism with respect to the double C=N bond and restricted rotation about the C(O)-N bond. Condensation products of 3-sulfanylpropionohydrazide with a series of aldoses give rise to ring-chain-ring tautomeric equilibrium between α,β-isomeric pyranose structures, open-chain aldose hydrazone tautomer, and two diastereoisomeric seven-membered cyclic 1,3,4-thiadiazepine forms.We previously showed that condensation products of carbonyl compounds with sulfanylacetic and 2-sulfanylbenzoic acid hydrazides in solution give rise to ring-chain tautomerism between linear acylhydrazone and cyclic 1,3,4-thiadiazine or 1,3,4-benzothiadiazepine structures, respectively [1][2][3][4][5]. In both cases, the cyclic tautomer is formed via intramolecular nucleophilic addition of the sulfanyl group at the C=N bond in the hydrazone fragment.…”

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“…We previously showed that condensation products of carbonyl compounds with sulfanylacetic and 2-sulfanylbenzoic acid hydrazides in solution give rise to ring-chain tautomerism between linear acylhydrazone and cyclic 1,3,4-thiadiazine or 1,3,4-benzothiadiazepine structures, respectively [1][2][3][4][5]. In both cases, the cyclic tautomer is formed via intramolecular nucleophilic addition of the sulfanyl group at the C=N bond in the hydrazone fragment.…”

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Structure of the condensation products of 3-sulfanylpropionic acid hydrazide with aldehydes, ketones, and aldoses

et al. 2009

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Condensation products of aliphatic aldehydes with 3-sulfanylpropionic acid hydrazide exist in solution as mixtures of linear hydrazone and cyclic 1,3,4-thiadiazepine tautomers. Hydrazones derived from 3-sulfanylpropionic acid hydrazide and aromatic aldehydes and ketones have mostly linear structures of different stereoisomers arising from Z-E isomerism with respect to the double C=N bond and restricted rotation about the C(O)-N bond. Condensation products of 3-sulfanylpropionohydrazide with a series of aldoses give rise to ring-chain-ring tautomeric equilibrium between α,β-isomeric pyranose structures, open-chain aldose hydrazone tautomer, and two diastereoisomeric seven-membered cyclic 1,3,4-thiadiazepine forms.We previously showed that condensation products of carbonyl compounds with sulfanylacetic and 2-sulfanylbenzoic acid hydrazides in solution give rise to ring-chain tautomerism between linear acylhydrazone and cyclic 1,3,4-thiadiazine or 1,3,4-benzothiadiazepine structures, respectively [1][2][3][4][5]. In both cases, the cyclic tautomer is formed via intramolecular nucleophilic addition of the sulfanyl group at the C=N bond in the hydrazone fragment. While continuing studies in this line, we examined the ability of condensation products formed by aldehydes, ketones, and aldoses with 3-sulfanylpropionic acid hydrazide to undergo ring-chain isomerism (Schemes 1, 2).We initially studied 3-sulfanylpropanoylhydrazones IIIa-IIIj derived from aliphatic and aromatic aldehydes and ketones. These compounds were synthesized in 40-85% yield by reaction of 3-sulfanylpropionohydrazide (II) with an equimolar amount of the corresponding carbonyl compounds Ia-Ij in methanol either at room temperature or on heating under reflux for a short time.3-Sulfanylpropionylhydrazones IIIa-IIIj can exist as linear tautomer A and seven-membered cyclic 1,3,4-thiadiazepine structure B. The latter could be formed via intramolecular addition of the SH group at the C=N bond in the hydrazone fragment. Furthermore, open-chain tautomer A may be represented by four stereoisomers with different configurations with respect to the C=N bond (Z-E isomerism) and C-N bond in the amide fragment (conformational Z′-E′ isomerism) [1, 2] (Scheme 1).Let us consider condensation products of hydrazide II with acetaldehyde, propionaldehyde, and butyraldehyde (compounds IIIa-IIIc). As follows from variation of the 1 H NMR spectra with time, these compounds in the crystalline state have structure A. The 1 H NMR spectrum of acetaldehyde hydrazone IIIa in DMSO-d 6 , recorded immediately after dissolution, contained two sets of signals assignable to two stereoisomers of linear tautomer A. The major stereoisomer (its fraction was 73% in the initial moment) was characterized by a quartet signal from the CH=N proton at δ 7.29 ppm, a triplet signal from the SH proton at 2.43 ppm, and a broadened singlet from the NH proton at δ 10.91 ppm. The corresponding signals of the minor stereoisomer (27%) were located at

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Ring-chain tautomerism of the condensation product of acetone with 2-sulfanylbenzohydrazide

Cited by 4 publications

References 2 publications

Thiosalicyloylhydrazones of aliphatic aldehydes and their cyclization to give 1,3,4-benzothiadiazepine derivatives

Thiosalicyloylhydrazones of aliphatic aldehydes and their cyclization to give 1,3,4-benzothiadiazepine derivatives

Structure of aldose condensation products with 2-hydroxyand 2-sulfanylbenzohydrazides

Structure of the condensation products of 3-sulfanylpropionic acid hydrazide with aldehydes, ketones, and aldoses

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