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Зеленин, K. Н.; Oleinik, S. V.; Алексеев, В. В.; Потехин, А. А.

doi:10.1023/a:1013126309514

Cited by 14 publications

(20 citation statements)

References 3 publications

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“…The signals of the (E')-isomer of this group are disposed at lower field than the analogous signals of the (Z')-isomer (Table 2). An opposite value of both signals in the 1 H NMR spectra is observed for the protons of the NHCO groups of the (E',Z')-conformers [6]. Taking into consideration the above-indicated it may be confirmed that the main isomer has the (E,Z')-structure, and the minor isomer the (E,E')-spatial disposition.…”

mentioning

confidence: 76%

Ring-chain tautomerism of 2-mercaptobenzoylhydrazones of aromatic aldehydes

Chernitsa

Еrshov

Doroshenko

et al. 2010

Chem Heterocycl Comp

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It was shown previously that 2-mercaptobenzoylhydrazones of aliphatic aldehydes exist in solution as tautomeric mixtures of linear and cyclic benzo-1,3,4-thiadiazepine forms. The position of the equilibrium was determined by the effective volume of the terminal alkyl substituent [1].The aim of the present work, being a continuation of the previous investigations, was to study the structure of the products of condensation of 2-mercaptobenzoic acid hydrazide with a series of aromatic aldehydes, and also the effect of the electronic properties of a substituent in the aromatic ring of the aldehyde component on the position of the tautomeric equilibrium.Compounds 2a-g were obtained in 65-90% yield after briefly maintaining equimolar quantities of 2-mercaptobenzoic acid hydrazide 1 and the appropriate aromatic aldehyde in methanol solution at 25 o C

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mentioning

confidence: 76%

Ring-chain tautomerism of 2-mercaptobenzoylhydrazones of aromatic aldehydes

Chernitsa

Еrshov

Doroshenko

et al. 2010

Chem Heterocycl Comp

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“…The signals of the E'-isomer of these groups are found at 145 and 170 ppm, while these signals are at 150 and 160 ppm for the Z'-isomer [10,11]. Thus, the chemical shifts given in Table 3 for the C=N and C=O bond carbon atoms of form A in 2e and 2f correspond to the E,Z'-arrangement of the thiosalicyloylhydrazone fragment.…”

mentioning

confidence: 84%

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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“…However, neither prolonged heating of typical representatives of compounds 4 and 5 in pyridine at 70°C, nor their treatment with sodium methylate in alcohol with subsequent neutralization resulted in any isomerisation. Hence, acetoacetylhydrazones, similarly to the closely related cyanoacetylhydrazones, 10 do not exhibit ring-chain tautomerism in solution.…”

Section: Mass Spectrometrymentioning

confidence: 95%

Synthesis and structural characterization of N-acetoacetylhydrazones and 2,5,5-trisubstituted 4-acetyl-3-pyrazolidinones

Зеленин¹,

Oleinik²,

Potekhin³

et al. 2003

Arkivoc

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Reaction of diketene with N-substituted hydrazones of aldehydes and sterically crowded ketones leads to the corresponding N-acetoacetylhydrazones. With hydrazones of other ketones, this reaction yields cyclic isomers of N-acetoacetylhydrazones, namely, 2,5,5-trisubstituted 4-acetylpyrazolidin-3-ones. The products where characterized by 1 H and 13 C NMR and electron ionization (EI) mass spectrometry. The EI mass spectra of the latter compounds and those of linear N-acetoacetylhydrazones show that in the gas phase their molecular ions attain predominantly similar forms as the respective neutral compounds in solutions. The mass-spectrometric fragmentation of both forms is characterized by retrosynthetic cleavages with the loss of neutral acetylketene. The imines produced from 2,5,5-trisubstituted 4-acetyl-3-pyrazoli-dinones and primary amines predominantly exist in solutions in the enamine form. The EI mass spectra of these condensation products show that in the gas phase their molecular ions exist as pyrazolidinones. Characteristic fragmentation paths under the EI conditions include the pyrazolidine ring cleavages at the N1-C5 and C3-C4 bonds, with the positive charge mainly localized in the enamine moiety. There is no evidence for ring-chain isomerism of the compounds studied.

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Cited by 14 publications

References 3 publications

Ring-chain tautomerism of 2-mercaptobenzoylhydrazones of aromatic aldehydes

Ring-chain tautomerism of 2-mercaptobenzoylhydrazones of aromatic aldehydes

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

Synthesis and structural characterization of N-acetoacetylhydrazones and 2,5,5-trisubstituted 4-acetyl-3-pyrazolidinones

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