Synthesis of 1-[3,5-bis-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-2,4,6-trihydroxyphenyl]ethanone: An intermediate of potential usefulness for synthesis of bis-C-glucosyl flavonoids

Bis-glycosylation of 3,5-dibenzyloxyphenol with 2,3,4,6-tetra-O-benzyl-α-d-glucopyranosyl fluoride in a two-step sequence produced the bis-glucosylated product, 3,5-dibenzyloxy-2,6-bis-(2,3,4,6-tetra-O-benzyl-β-d-glucopyranosyl)phenol. Subsequent hydrogenolytic debenzylation and acetylation gave the undeca-O-acetyl derivative, which, when subjected to a Friedel-Crafts acylation with borontrifluoride-acetic acid, gave the 4-C-acetyl target compound, 1-[3,5-bis-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-2,4,6-trihydroxyphenyl]ethanone.