Étude de la conformation de dérivés pyrroliques

Oussaid, B.; Hubert, Cathy; Moeini, Leila; Garrigues, Bernard; Fayet, Jean-Pierre

doi:10.1139/v93-082

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…The temperature coefficients of H1¢ for the E-isomer (7) and for the Z-isomer (8) are -1.2 and -4.4 ppb, respectively. These values indicate the presence of a hydrogen bond in 7, which implies that the (NH,C cis) form is the preferred conformer for the E-isomer.…”

Section: Conformational Analysismentioning

confidence: 96%

“…This conformational preference was rationalized through molecular orbital calculations (6). Analogously, the conformation of 2-substituted imine derivatives has also been studied through dipolar moment measurements and five-bond H,H couplings (7). These studies demonstrated the preponderance of the (NH,N cis) conformer in solution, which was also proposed to be stabilized by a hydrogen bond.…”

Section: Conformational Analysismentioning

confidence: 99%

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Structural and conformational studies of 5-(1H-pyrrol-2-ylmethylene)-substituted imidazolidine-2,4-diones and thiazolidine-2,4-diones

Dios¹,

Puente²,

Rivera‐Sagredo³

et al. 2002

Can. J. Chem.

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Some imidazolidine-2,4-dione (hydantoin) and thiazolidine-2,4-dione (TZD) derivatives with a 1H-pyrrol-2-ylmethylene substituent at the 5-position (1-8) have been synthesized via an aldol condensation reaction. A mixture of Z-and E-stereoisomers was obtained, as confirmed by HPLC and NMR studies. Assignment of the stereochemistry was achieved through chemical shift knowledge, NOE, and 3 J H,C data. The conformation of the molecules depends on the configuration at the double bond. While the (NH,C cis) form is the most stable conformer for the E-isomer, the (NH,C trans) form is the preferred conformer for the Z-isomer. The temperature coefficients of the NH pyrrole protons reveal the existence of an intramolecular hydrogen bond for the E-isomers.Résumé : Faisant appel à une réaction de condensation aldolique, on a réalisé la synthèse de dérivés de l'imidazolidine-2,4-dione (hydrantoïne) et de la thiazolidine-2,4-dione (TZD) portant un substituant 1H-pyrrol-2-ylméthylène en position 5 (1-8). La formation de mélanges de stéréoisomères Z-et E-a été confirmée par des études de CLHP et de RMN. L'attribution de la stéréochimie a été réalisée sur la base de connaissances chimiques et de données relatives aux valeurs 3 J H,C et d'effet Overhauser nucléaire. La conformation des molécules dépend de la configuration de la double liaison. Alors que le forme NH,C cis correspond à la conformation la plus stable de l'isomère E, la forme NH,C trans correspond à la conformation la plus stable de l'isomère Z. Les coefficients de température des protons NH du pyrrole mettent en évidence l'existence d'une liaison hydrogène intramoléculaire pour les isomères E.

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Section: Conformational Analysismentioning

confidence: 96%

Section: Conformational Analysismentioning

confidence: 99%

Structural and conformational studies of 5-(1H-pyrrol-2-ylmethylene)-substituted imidazolidine-2,4-diones and thiazolidine-2,4-diones

Dios¹,

Puente²,

Rivera‐Sagredo³

et al. 2002

Can. J. Chem.

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Mise au Point Sur la Conformation de Derives Thiopheniques

Garrigues

Oussaid

Moeini

et al. 1995

Bulletin des Soc Chimique

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In this review an account of the numerous works related to the determination of the conformation in solution of thiophenic compounds is given . Most of the studies were effected by dipole moment measurement, infrared and microwave absorption, or theoretical calculations. NMR spectrometry was employed as a priviledged tool in many cases, using the measurements of the stereospecific coupling constants across five bonds. An interpretation of the results is proposed.

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