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Medientyp:
E-Artikel
Titel:
Structural and conformational studies of 5-(1H-pyrrol-2-ylmethylene)-substituted imidazolidine-2,4-diones and thiazolidine-2,4-diones
Beteiligte:
Dios, Alfonso de;
de la Puente, Maria Luz;
Rivera-Sagredo, Alfonso;
Espinosa, Juan Felix
Erschienen:
Canadian Science Publishing, 2002
Erschienen in:Canadian Journal of Chemistry
Sprache:
Englisch
DOI:
10.1139/v02-175
ISSN:
0008-4042;
1480-3291
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p> Some imidazolidine-2,4-dione (hydantoin) and thiazolidine-2,4-dione (TZD) derivatives with a 1H-pyrrol-2-ylmethylene substituent at the 5-position (18) 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 <jats:sup>3</jats:sup>J<jats:sub>H,C</jats:sub> 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.Key words: hydantoin, TZD, NMR spectroscopy, conformational analysis, temperature coefficient. </jats:p>