Stereochemical Properties of Glucosyl Sulfoxides in Solution
详细信息 查看全文
- 作者：Carlos A. Sanhueza ; Rosa L. Dorta ; Jesu虂s T. Va虂zquez
- 刊名：Journal of Organic Chemistry
- 出版年：2011
- 出版时间：October 7, 2011
- 年：2011
- 卷：76
- 期：19
- 页码：7769-7780
- 全文大小：1104K
- 年卷期：v.76,no.19(October 7, 2011)
- ISSN：1520-6904
文摘
A series of alkyl 尾-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鈥揅6 (hydroxymethyl group) bonds were studied. The results for RS sulfoxides show linear correlations between the rotamer populations of the hydroxymethyl group and the corresponding Taft鈥檚 steric parameter (ES) of the alkyl group attached to the sulfinyl group in polar and apolar solvents, an increase in the absolute value of ES 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鈥?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 RS sulfoxides. Sulfoxides with the SS configuration show different behavior to their RS epimers; thus, an increase in the ES 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鈥?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.