Nuclear magnetic resonance spectra and structures of some C-glycosyl flavonoids

Abstract

From an examination of the nuclear magnetic resonance spectra, optical rotations, and other properties of a number of flavonoid C-glycosides, their acetates, and related model compounds, it is concluded that vitexin, bayin, puerarin, and isohemiphloin are C-β-D-glucosides with the sugar substituent in the 8-position of the flavonoid nucleus. Hemiphloin and saponaretin are two of the corresponding 6-substituted compounds. In hemiphloin and isohemiphloin the phenyl B ring has the equatorial configuration.