Carthamin acetate, (3S,3'S)-1-[5-(p-acetoxycinnamoyl)-3-C- (beta -D-2", 3",4", 6" -tetra-O-acetylglucopyranosyl)-3,4-dihydroxy-2,6-diketo]cyclohex-4-enyli dene-1'-[5'-(p-acetoxycinnamo-yl)-3'-C-(beta -D-2"',3"',4"',6"'-tetra-O-acetylglucopyranosyl)-2', 3',4'-trihydroxy-6'-keto]cyclohexa-1',4'-dienylmethane 7a and its (3R,3'R)-epimer 7b were synthesized via the C-glycosylation of 2-acetyl-1,3,4,5-benzenetetrol using acetobromoglucose in the presence of sodium hyride, followed by aldol condensation with p-hydroxybenzaldehyde after methyl-protection of the enolic hydroxy group, and subsequent dimerization with triethyl orthoformate after demethylation, in a total yield of 0.6%. Their absolute configurations were determined by X-ray analysis of the key intermediate 4b.