Department of Chemistry, University of Debrecen, Debrecen, Hungary.
Magn Reson Chem. 2011 Apr;49(4):190-4. doi: 10.1002/mrc.2731. Epub 2011 Mar 9.
Selenoglycosides are important starting materials in synthetic carbohydrate chemistry and play a role in biological interactions as well. Both aspects are influenced by the conformation around the glycosidic bond. Here, we present a combined experimental and computational approach to measure and evaluate (n)J((77)Se, (1)H) coupling constants for their use in conformational analysis. The measurements were carried out using a modified CPMG-HSQMBC pulse scheme which yields pure absorption antiphase multiplets to allow accurate determination of the (n)J(XH) values regardless of the size of the proton-proton couplings. Theoretical calculations were performed at the Second-Order Polarization Propagator Approach (SOPPA) level. Population-averaged values calculated for geminal and vicinal couplings are in a good agreement with experiment indicating an adequate theoretical level of the calculations. Experimental observations and computations alike have indicated that two-bond (77)Se-(1)H couplings, (2)J((77)Se, (1)H), in a H1-C1-Se-X moiety are very sensitive to the torsion angle around the C1-Se-bond and will, therefore, be useful for conformational studies.
硒糖苷是合成碳水化合物化学中的重要起始材料，在生物相互作用中也发挥作用。这两个方面都受到糖苷键周围构象的影响。在这里，我们提出了一种结合实验和计算的方法来测量和评估（n）J（（77）Se，（1）H）耦合常数，用于构象分析。测量是使用改进的 CPMG-HSQMBC 脉冲方案进行的，该方案产生纯吸收反相多重峰，允许无论质子-质子偶合的大小如何，都能准确确定（n）J（（XH）值。理论计算是在二阶极化传播器方法（SOPPA）水平上进行的。计算得到的偕二和邻位偶合的平均种群值与实验值吻合较好，表明计算的理论水平足够。实验观察和计算都表明，在 H1-C1-Se-X 部分中，两个键（77）Se-（1）H 偶合（2）J（（77）Se，（1）H）对 C1-Se 键周围的扭转角非常敏感，因此将有助于构象研究。
