Dynamic stereochemistry of rutin (vitamin P) in solution: theoretical approaches and experimental validation

Rutin, vitamin P, was extracted from Salvia macrosiphon and identified by (1)H, (13)C, (1)H-(1)H COSY, HMQC, and HMBC spectroscopy. In parallel, density functional theory (DFT) using B(3)LYP functional and split-valance 6-311G * * basis set has been used to optimize the structures and conformers of rutin. Also experimental and theoretical methods have been used to correlate the dependencies of (1)J, (2)J, and (3)J involving (1)H and (13)C on the C5''-C6'' (omega), C6''-O6'' (theta), and C1'''-O6'' (phi) torsion angles in the glycosidic moiety. New Karplus equations are proposed to assist in the structural interpretation of these couplings. (3)J(HH) depends mainly on the C-C (omega) torsion angle, as expected, and (2)J(HH) values depend on both C-C (omega) and C-O (theta) torsions. (1)J(CH) values within hydroxymethyl fragments were also examined and found to depend on r(CH), which is modulated by specific bond orientation and stereoelectronic factors. In all calculations solvent effects were considered using a polarized continuum model (PCM).