13C Nuclear Magnetic Resonance Spectra of Hydrolyzable Tannins. III.1) Tannins Having 1C4Glucose and C-Glucosidic Linkage

Abstract

Two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy was utilized for the assignments of the glucose carbon signals in the 13C-NMR spectra of hydrolyzable tannins in which the glucopyranose core takes a 1C4or related boat conformation, and of tannins possessing a C-glucosidic linkage. Remarkable changes in the sequences of glucose carbons were observed with change in the conformation of the glucose core, and with the formation of a C-glucosidic linkage. The chemical shifts of the C-2 signals of the glucose cores adopting the open-chain form in C-glucosidic tannins and in complex tannins can be utilized for the discrimination of the configurations at C-l in these tannins. © 1988, The Pharmaceutical Society of Japan. All rights reserved.