Intermolecular and intramolecular hydrogen bonding in 5‐pyridylmethylenehydantoins: IR and NMR study

Tan, Siong Kiat; Ang, K. P.; How, Gee Fung

doi:10.1002/poc.610040308

Cited by 11 publications

(1 citation statement)

References 13 publications

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“…Orthosubstituents at the benzene ring increase this twist up to 46 ~ [15,29]. The E/Z isomerism of the pyridyl (Scheme 4), thienyl, furyl, and crotonyl analogues was assigned by employing the same proton chemical shifts [26,28,34] and the NH stretching vibrations [27]; in addition, the Z isomers of the hydantoins with 2-or 3-pyridyl rings prefer an s-cis conformation (due to intramolecular hydrogen bonding), whereas the E isomers prefer an s-trans conformation (Scheme 4 for 2-pyridyl analogues) due to repulsion between the lone pairs on the pyridyl nitrogen and on the C-4 carbonyl oxygen [28].…”

Section: E/z Isomerism Of 5-exo-methylene Hydantoinsmentioning

confidence: 99%

The structure of hydantoins in solution and in the solid state

Kleinpeter

1997

Struct Chem

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The results of NMR spectroscopic and X-ray crystallographic studies are critically discussed with respect to the structure of hydantoins, their tautomerism, and their acidity. The imide NH proton of the preferred, nearly planar 2,4-imidazolidine-dione tautomer proved to be more acidic than the corresponding amide NH proton. Phenyl substituents at the ring nitrogen atoms and at C-5 are twisted from the plane of the hydantoin ring; in case of ortho substituents restricted rotation about the N-aryl bond was found and the barrier to rotation determined by dynamic NMR spectroscopy.For 5-benzyl substituents, a folded conformation of the two rings, due to intramolecular interactions, was found and for 5-exo-methylene substituted hydantoins the relevant E/Z isomerism at the exo-cyclic C, C double bond was studied. In addition, the IH and 13C chemical shifts of the hydantoins proved to excellently indicate the electronic distribution along the hydantoin ring moiety. Finally, the mass spectrometric fragmentation of the hydantoins is critically discussed.

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Section: E/z Isomerism Of 5-exo-methylene Hydantoinsmentioning

confidence: 99%

The structure of hydantoins in solution and in the solid state

Kleinpeter

1997

Struct Chem

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Synthesis and NMR study of 5‐furylmethylenehydantoins and 5‐thienylmethylenehydantoins

Tan

How

Yeoh

1991

J of Physical Organic Chem

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Two series of 5‐furylmethylenehydantoins and 5‐thienylmethylenehydantoins were prepared and their 1H and 13C NMR spectra studied in comparison with those of compounds in the analogous 5‐aryl‐ and 5‐pyridyl‐ series. Differences in the effects of the aromatic, six‐ or five‐membered heteroaromatic rings are discussed. Spectral analysis enables Z/E configurations to be assigned with confidence and conformational preferences to be qualitatively deduced. Some interesting solvent effects were also observed.

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Z/E, photoisomerization of 5‐arylmethylenehydantoins and 5‐pyridylmethylenehydantoins

Tan¹,

Ang²,

How³

1991

J of Physical Organic Chem

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The Z/E photoisomerization of a series of 5‐arylmethylenehydantoins and a series of 5‐pyridylmethylenehydantoins by direct irradiation in methanol or ethanol solvent was investigated. The isomeric ratios at the photostationary state are dependent on the excitation wavelength and are related to the relative absorption coefficients of the two isomers. Measurements of quantum yields show the absence of quenching effects by oxygen or azulene, suggesting that triplet states either are not involved or are too short‐lived for quenching to be observed. Preparative photoisomerization provides a route to the isomer which is not isolated or obtained only as a minor product by the usual method of synthesis.

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Intermolecular and intramolecular hydrogen bonding in 5‐pyridylmethylenehydantoins: IR and NMR study

Cited by 11 publications

References 13 publications

The structure of hydantoins in solution and in the solid state

The structure of hydantoins in solution and in the solid state

Synthesis and NMR study of 5‐furylmethylenehydantoins and 5‐thienylmethylenehydantoins

Z/E, photoisomerization of 5‐arylmethylenehydantoins and 5‐pyridylmethylenehydantoins

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