Total synthesis of three naturally occurring 6,8-di-C-glycosylflavonoids:phloretin,naringenin,and apigenin bis-C-beta-D-glucosides

摘要

Three naturally occurring di-C-glycosylflavonoids,phloretin (dihydrochalcone),naringenin (flavanone),and apigenin (flavone)bis-6,8-C-beta-D-glucopyranosides (4,5,and 6),were synthesized in total yields of 52.3%,53.5%,and 36.4%,respectively,starting from the key compound,di-C-beta-D-glucopyranosylphloroacetophenone (1).Benzyl protection of the phenolic hydroxyls in 1 and a subsequent aldol condensation with benzyloxybenzaldehyde led to the production of chalcone 3,which,after hydrogeno-lysis or acid hydrolysis and deprotection,gave 4 and 5,respectively.The acetylation of 5,followed by DDQ oxidation and depro-tection,gave 6.