Determination of the absolute stereochemistry of chiral secondary megastigmane alcohols from Shiraz leaves by NMR studies

The configuration of the chiral secondary alcohols of a megastigmane-3,9-di ol was determined using ROESY experiments performed on its peracetylated be ta -D-glucopyranosides, previously isolated from Vitis Vinifera Shiraz leav es. On the basis of the data available for structurally related disaccharid es, the rules reported previously to determine the conformation of disaccha ride linkage were applied to predict the applicability of this method to ot her chiral secondary alcohols with no or only one bulky substituent on the beta -carbons. That would lend additional support to the applicability of t he method based on the beta -effects of glycosylation in C-13-NMR.