Stilbene glycosides from Guibourtia coleosperma: determination of glycosidic connectivities by homonuclear nuclear Overhauser effect difference spectroscopy

Abstract
Two novel stilbene glycosides, 3,4′-dimethoxy- and 3,3′-dihydroxy-4′-methoxy-5-[O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranosyloxy]stilbene, have been obtained from Guibourtia coleosperma. Connectivities of glycosidic moieties in these and other mono- and bio-sides have been established by 1H n.m.r. nuclear Overhauser effect difference spectroscopy. Such an approach may prove useful in cases where alternative methods towards achieving the same goal are hampered by limited sample quantitites.