Novel and efficient synthesis of cyanidin 3-O-β-D-glucoside from (+)-catechin via a flav-3-en-3-ol as a key intermediate

A novel and efficient synthesis of cyanidin 3-O-beta-D-glucoside (1) was accomplished the first time by a biomimetic oxidation route. From (+)-catechin, 3-OH was glucosylated, and the 4-position of the nucleus was then oxidized and dehydrated to give the 5,7,3', 4'-tetra-O-(tertbutyldimethylsilyl) flav-3-en-3-ol-3-O-glucoside (8) as a key intermediate. 8 was deprotected and oxidized under air in hydrogen chloride-MeOH to give 1.