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-diol was determined using ROESY experiments performed on its peracetylated beta -D-glucopyranosides, previously isolated from Vitis Vinifera Shiraz leaves. On the basis of the data available for structurally related disaccharides, the rules reported previously to determine the conformation of disaccharide linkage were applied to predict the applicability of this method to other chiral secondary alcohols with no or only one bulky substituent on the beta -carbons. That would lend additional support to the applicability of the method based on the beta -effects of glycosylation in C-13-NMR.