title: Experimental and DFT 1H NMR study of conformational equilibria in trans-4',7-dihydroxyisoflavan-4-ol and trans-isoflavan-4-ol.
abstract: The solution-state conformational equilibria of trans-4',7-dihydroxyisoflavan-4-ol (1) and trans-isoflavan-4-ol (2) were assessed based on the temperature dependence of their vicinal coupling constants J(H)(-)(2)(alpha)(,H)(-)(3) and J(H-3,H)(-)(4) in comparison to values calculated with density functional theory (DFT) methods at the B3LYP/cc-pVTZ//B3LYP/6-31G(d,p) level of theory. For each half-chair conformer, several rotamers with respect to the C-4 hydroxyl and C-3 phenyl were calculated and the overall diequatorial-to-diaxial ratio at 298 K was assessed as 66:34 for 1 and 73:27 for 2. The syntheses of 1 and 2 are described.
authors.affiliation: Structural Chemistry Group, Department of Chemistry, University of Turku, Vatselankatu 2, FIN-20014 Turku, Finland. kalevi.pihlaja@utu.fi
authors.forename: Kalevi
authors.initials: K
authors.lastname: Pihlaja
authors.forename: Petri
authors.initials: P
authors.lastname: Tähtinen
authors.forename: Karel D
authors.initials: KD
authors.lastname: Klika
authors.forename: Tuija
authors.initials: T
authors.lastname: Jokela
authors.forename: Auli
authors.initials: A
authors.lastname: Salakka
authors.forename: Kristiina
authors.initials: K
authors.lastname: Wähälä