Heterocyclic tautomerism. VI. A redetermination and reassignment of the structure of 2-aminothiazol-4(5H)-one (pseudothiohydantoin)

Steel, P. J.; Guard, J. A. M.

doi:10.1107/s0108270194004750

Cited by 6 publications

(5 citation statements)

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“…Selected interatomic distances are collected in Table . The obtained ab initio results for the geometry of tautomer B of 2AT are in agreement with the available X-ray data …”

Section: Resultsmentioning

confidence: 98%

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Ab Initio Study of 2,4-Substituted Azolidines. II. Amino−Imino Tautomerism of 2-Aminothiazolidine-4-one and 4-Aminothiazolidine-2-one in Water Solution

2005

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The relative stabilities of the tautomers of 2-aminothiazolidine-4-one and 4-aminothiazolidine-2-one were calculated at the MP2/6-31+G(d,p) level by considering their mono- and trihydrated complexes. Single-point calculations at the MP4/6-31+G(d,p)//MP2/6-31+G(d,p) level of theory were performed to obtain more accurate energies. The values of proton transfer barriers in the isolated, mono- and trihydrated tautomers of 2-aminothiazolidine-4-one (2AT) and 4-aminothiazolidine-2-one (4AT) were calculated for two different mechanisms of tautomerisation. In the absence of water, the process of proton transfer should not occur. Addition of water molecules decreases the barrier making the process faster, as the participation of two water molecules in a proton transfer reaction is more favorable than the participation of only one water molecule. To estimate the effect of the medium (water) on the relative stabilities of the tautomers of the studied compounds we applied the polarizable continuum model (PCM). (13)C NMR chemical shieldings were calculated using the GIAO approach at MP2/6-31+G(d,p) optimized geometries. HF and the DFT B3LYP functional with 6-31+G(d,p) basis set were employed. The quantum chemical results for the chemical shifts in gas phase and in polar solvents (water and DMSO) were compared with experimental data. TD DFT B3LYP/aug-cc-pVTZ calculations were performed to predict the absorption maxima of tautomers A and B of 2AT and 4AT.

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“…Selected interatomic distances are collected in Table . The obtained ab initio results for the geometry of tautomer B of 2AT are in agreement with the available X-ray data …”

Section: Resultsmentioning

confidence: 98%

“…Experimental studies on the amino-imino tautomerism of 2-aminothiazolidine-4-one have been reported in several papers. − However, the opinions of the authors are contradictory. Amirthalingam and Muralidharan 7 have confirmed by X-ray the existence of the imino form of pseudothiohydantoin.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Study of 2,4-Substituted Azolidines. II. Amino−Imino Tautomerism of 2-Aminothiazolidine-4-one and 4-Aminothiazolidine-2-one in Water Solution

2005

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“…77,78 The discussion on the tautomerism of this molecule continued for more than a century. 79 Today, commercial availability of a great variety of aryl and alkyl isothiocyanates gives easy access to thioureas and therefore makes the pathway in Scheme 1 very attractive for a rapid assembly of a large array of substituted 2-imino-thiazolidin-4-one scaffolds. Thus, reacting an aryl or alkyl isothiocyanate with a primary amine furnished the corresponding thiourea derivative, which was directly cyclized to the iminothiazolidinone by treating this intermediate with a bromoacetic acid ester in the presence of pyridine.…”

Section: Chemistrymentioning

confidence: 99%

“…Several synthetic routes give access to substituted 2-imino-thiazolidin-4-ones. − The cyclization of substituted thioureas with a halo acetic acid derivative to form the corresponding 2-imino-thiazolidin-4-one has been described almost one and a half centuries ago, − albeit the structure of the isolated products was originally assigned, incorrectly, as 2-thiohydantoin. The correct constitution of the 2-imino-thiazolidin-4-one, also known as pseudothiohydantoin, was first proposed by Liebermann et al in 1879. , The discussion on the tautomerism of this molecule continued for more than a century . Today, commercial availability of a great variety of aryl and alkyl isothiocyanates gives easy access to thioureas and therefore makes the pathway in Scheme very attractive for a rapid assembly of a large array of substituted 2-imino-thiazolidin-4-one scaffolds.…”

Section: Chemistrymentioning

confidence: 99%

2-Imino-thiazolidin-4-one Derivatives as Potent, Orally Active S1P₁Receptor Agonists

Bolli¹,

Abele²,

Binkert³

et al. 2010

J. Med. Chem.

167

134

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Sphingosine-1-phosphate (S1P) is a widespread lysophospholipid which displays a wealth of biological effects. Extracellular S1P conveys its activity through five specific G-protein coupled receptors numbered S1P(1) through S1P(5). Agonists of the S1P(1) receptor block the egress of T-lymphocytes from thymus and lymphoid organs and hold promise for the oral treatment of autoimmune disorders. Here, we report on the discovery and detailed structure-activity relationships of a novel class of S1P(1) receptor agonists based on the 2-imino-thiazolidin-4-one scaffold. Compound 8bo (ACT-128800) emerged from this series and is a potent, selective, and orally active S1P(1) receptor agonist selected for clinical development. In the rat, maximal reduction of circulating lymphocytes was reached at a dose of 3 mg/kg. The duration of lymphocyte sequestration was dose dependent. At a dose of 100 mg/kg, the effect on lymphocyte counts was fully reversible within less than 36 h. Pharmacokinetic investigation of 8bo in beagle dogs suggests that the compound is suitable for once daily dosing in humans.

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“…1 . According to Taylor and coworkers and Steel et al [ 31 , 11 , 12 , 17 ] the Z -isomer predominates when H-bonding occurs, otherwise this isomer is impossible. In other conditions, the E isomer is the stable form.…”

Section: Resultsmentioning

confidence: 99%

Conformational space and vibrational spectra of 2-[(2,4-dimethoxyphenyl)amino]-1,3-thiazolidin-4-one

et al. 2014

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In this work we present the results of a study of the X-ray structure of 2-[(2,4-dimethoxyphenyl)amino]-1,3-thiazolidin-4-one. Using the FTIR spectra in solid state and results of ab initio calculations we explain the issue of the tautomerism of this molecule. The compound is shown to exist as the 2-amino tautomer rather 2-imino tautomer. Here we consider eight possible tautomers. On the basis of the vibrational spectra we can eliminate five possible tautomers, as not existing in the solid state. As the most possible tautomeric form we have found keto 2-amino form.Electronic supplementary materialThe online version of this article (doi:10.1007/s00894-014-2366-6) contains supplementary material, which is available to authorized users.

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Heterocyclic tautomerism. VI. A redetermination and reassignment of the structure of 2-aminothiazol-4(5H)-one (pseudothiohydantoin)

Cited by 6 publications

References 1 publication

Ab Initio Study of 2,4-Substituted Azolidines. II. Amino−Imino Tautomerism of 2-Aminothiazolidine-4-one and 4-Aminothiazolidine-2-one in Water Solution

Ab Initio Study of 2,4-Substituted Azolidines. II. Amino−Imino Tautomerism of 2-Aminothiazolidine-4-one and 4-Aminothiazolidine-2-one in Water Solution

2-Imino-thiazolidin-4-one Derivatives as Potent, Orally Active S1P₁Receptor Agonists

Conformational space and vibrational spectra of 2-[(2,4-dimethoxyphenyl)amino]-1,3-thiazolidin-4-one

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Heterocyclic tautomerism. VI. A redetermination and reassignment of the structure of 2-aminothiazol-4(5H)-one (pseudothiohydantoin)

Cited by 6 publications

References 1 publication

Ab Initio Study of 2,4-Substituted Azolidines. II. Amino−Imino Tautomerism of 2-Aminothiazolidine-4-one and 4-Aminothiazolidine-2-one in Water Solution

Ab Initio Study of 2,4-Substituted Azolidines. II. Amino−Imino Tautomerism of 2-Aminothiazolidine-4-one and 4-Aminothiazolidine-2-one in Water Solution

2-Imino-thiazolidin-4-one Derivatives as Potent, Orally Active S1P1Receptor Agonists

Conformational space and vibrational spectra of 2-[(2,4-dimethoxyphenyl)amino]-1,3-thiazolidin-4-one

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Product

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2-Imino-thiazolidin-4-one Derivatives as Potent, Orally Active S1P₁Receptor Agonists