First Chemical Synthesis of Three Natural Depsides Involved in Flavonol Catabolism and Related to Quercetinase Catalysis

Abstract We report here the first chemical synthesis of three depsides related to quercetinase‐catalyzed degradation of kaempferol, quercetin, and myricetin. The three depsides were constructed through the coupling of suitably protected phloroglucinol carboxylic acid and hydroxy‐perbenzylated, derivatives of gallic, protocatechuic, and 4‐hydroxy benzoic acids. The three synthesized target compounds proved to be identical to their natural counterparts, arising from quercetinase action on corresponding flavonols.