Synthesis of 3-O-(β-d-xylopyranosyl-(1→2)-β-d-glucopyranosyl)-3′-O-(β-d-glucopyranosyl)tamarixetin, the putative structure of aescuflavoside A from the seeds of Aesculus chinensis

3-O-(β-d-Xylopyranosyl-(1→2)-β-d-glucopyranosyl)-3′-O-(β-d-glucopyranosyl)tamarixetin, the putative flavonal glycoside named aescuflavoside A, isolated from the seeds of Aesculus chinensis, is synthesized via regioselective glycosylation of 7-O-benzyltamarixetin with glycosyl bromides under phase-transfer-catalyzed conditions.