Kurtán Tibor, Borbás Anikó, Szabó Zoltán B, Lipták András, Bényei Attila, Antus Sándor
Department of Organic Chemistry, University of Debrecen, Debrecen, Hungary.
Chirality. 2004 May 5;16(4):244-50. doi: 10.1002/chir.20019.
The CD spectra are reported for a series of 1,3-dioxane-type 4,6-O-(2'-naphthyl)methylene acetals of carbohydrates with and without interacting aromatic protective groups on the C-1, C-2, and C-3 hydroxy groups. In the absence of interacting chromophores, the signs of the (1)B transitions are not sensitive to the configuration of C-4, while the signs of the weak (1)L(a) bands are opposite in the galacto and gluco derivatives. The equatorial parallel conformation is found to be the preferred conformation of the 2-naphthyl group in the solid state by X-ray diffraction. The intense (1)B(a) and (1)B(b) transitions of the naphthalene chromophore allowed a safe configurational assignment by exciton coupled interaction with the aromatic protective groups in para-methoxyphenyl-beta-D-glycosides. The origin of the observed CEs were deduced and the additivity of the interactions was studied. The direction of the hydrogenolytic cleavage of 4,6-O-(2'-naphthyl)methylene acetal of carbohydrates could also be detected by the (1)B(b) transition of the 2-naphthyl chromophore.
报道了一系列碳水化合物的1,3 - 二氧六环型4,6 - O -（2'-萘基）亚甲基缩醛的圆二色光谱，这些碳水化合物在C - 1、C - 2和C - 3羟基上有或没有相互作用的芳香保护基团。在没有相互作用发色团的情况下，(1)B跃迁的符号对C - 4的构型不敏感，而弱(1)L(a)带的符号在半乳糖和葡萄糖衍生物中相反。通过X射线衍射发现，在固态中，2 - 萘基的赤道平行构象是优选构象。萘发色团强烈的(1)B(a)和(1)B(b)跃迁通过与对甲氧基苯基 - β - D - 糖苷中的芳香保护基团的激子耦合相互作用实现了可靠的构型归属。推导了观察到的圆二色性效应的起源，并研究了相互作用的加和性。碳水化合物的4,6 - O -（2'-萘基）亚甲基缩醛的氢解断裂方向也可以通过2 - 萘基发色团的(1)B(b)跃迁检测到。
