C-Glycosylflavonoids. II. The synthesis of 7,4'-Di-O-methylpuerarin (8-C-β-D-Glucopyranosyl-7,4'-dimethoxyisoflavone)

Abstract

The product of reaction of 2'-acetoxy-4,4'-dimethoxy-3'-(tetraacetyl-β-D-glucopyranosyl)chalcone (4) with thallium(III) nitrate in methanol/trimethyl orthoformate solution gave, after acid hydrolysis, a high yield of 7,4'-di-O-methylpuerarin (2). The dimethyl acetal (6) and the enol ether (7) have been isolated from the reaction of the chalcone (4) with thallium(III) nitrate in methanol. Both the acetal (6) and ether (7) gave 7,4'-di-O-methylpuerarin on reaction with acid or base.