title: Stereochemical properties of glucosyl sulfoxides in solution.
abstract: A series of alkyl β-glucosyl sulfoxides were synthesized and characterized in order to study their stereochemical properties. The dependence of the aglycon, solvent and absolute configuration of the sulfinyl group on the conformational properties around the glucosidic and C5-C6 (hydroxymethyl group) bonds were studied. The results for R(S) sulfoxides show linear correlations between the rotamer populations of the hydroxymethyl group and the corresponding Taft's steric parameter (E(S)) of the alkyl group attached to the sulfinyl group in polar and apolar solvents, an increase in the absolute value of E(S) leading to an increase in the gt population. In addition, NOE experiments reveal that as the bulkiness of the alkyl group increases the population of the g- rotamer increases, the latter stabilized by the exo-anomeric effect. These results are in complete agreement with the participation of the exo-anomeric effect in both conformational properties of R(S) sulfoxides. Sulfoxides with the S(S) configuration show different behavior to their R(S) epimers; thus, an increase in the E(S) value of the alkyl group leads to similar or lower gt populations in apolar solvents and to increases in gt in polar solvents. Their NOE studies reveal a conformational equilibrium (in polar and apolar solvents) between g- and g+, dependent on the size of the alkyl group R attached to the sulfinyl group. All these results for both epimers support the general hypothesis that the exo-anomeric effect modifies the conformation of the hydroxymethyl group, fulfills the stereoelectronic requirements, and shows dependence on the solvent.
authors.affiliation: Instituto Universitario de Bio-Orgánica Antonio González, Departamento de Química Orgánica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Sanhueza
authors.forename: Rosa L
authors.initials: RL
authors.lastname: Dorta
authors.forename: Jesús T
authors.initials: JT
authors.lastname: Vázquez
mesh_terms: D002942:Circular Dichroism; D005947:Glucose / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D013454:Sulfoxides / Q000737:chemistry*
chemical_list: D012996:Solutions; D012997:Solvents; D013454:Sulfoxides; D005947:Glucose