21 加水分解性タンニンオリゴマーおよび関連タンニンのNMRとMSスペクトル解析

概要

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New way of applying ^<13>C-NMR and MS spectra for the structural assignments of oligomeric hydrolyzable tannins have been developed. (I) The FAB-MS measurements of several monomeric and dimeric hydrolyzable tannins proved that FAB-MS can be applied for the determination of the molecular weights of these tannins without derivatization. (II) Full assignments of the glucose carbon signals of hydrolyzable tannins in the ^<13>C NMR spectra have been accomplished by {^1H}-^<13>C selective decoupling. These results gave following conclusions. (a) The peak sequences of carbons in glucose are different among several types of hydrolyzable tannins, reflecting the difference of acyl (galloyl, HHDP and DHHDP) groups on the ^4C_1 glucopyranose ring, as found upon comparison of penta-O-galloyl-β-D-glucopyranose (5), casuarictin (11), tellimagrandin II (17) and isoterchebin (19). (b) The additive parameters of galloylation and hexahydroxydiphenoylation shifts can be used for locating the position of acyl group. (c) The substituents and substitution mode at C-1 and C-2 of glucose core can be deduced based on the ^<13>C chemical shift of the anomeric carbon signal. (d) The ^<13>C resonances of the oligomeric hydrolyzable tannins can be assigned on the basis of the data for their monomeric units.
天然有機化合物討論会の論文
1983-09-15