C-glycosylanthocyanidins synthesized from C-glycosylflavones.

Nine C-glycosyldeoxyanthocyanidins, 6-C-beta-glucopyranosyl-7-O-methylapigeninidin, 6-C-beta-glucopyranosyl-7-O-methylluteolinidin, 6-C-beta-(2''-O-beta-glucopyranosylglucopyranosyl)-7-O-methylapigeninidin, 6-C-beta-(2''-O-beta-glucopyranosylglucopyranosyl)-7,4'-di-O-methylapigeninidin, 8-C-beta-glucopyranosylapigeninidin, 8-C-beta-(2''-O-alpha-rhamnopyranosylglucopyranosyl)apigeninidin, 8-C-beta-(2''-O-alpha-(4'''-O-acetylrhamnopyranosyl)glucopyranosyl)apigeninidin, 6,8-di-C-beta-glucopyranosylapigeninidin (8), 6,8-di-C-beta-glucopyranosyl-4'-O-methylluteolinidin (9), have been synthesized from their respective C-glycosylflavones (yields between 14% and 32%) by the Clemmensen reduction reaction using zinc-amalgam. The various precursors (C-glycosylflavones) of the C-glycosylanthocyanidins were isolated from either flowers of Iris sibirica L., leaves of Hawthorn 'Crataegi Folium Cum Flore', or lemons and oranges.