Structural modifications are an important tool for studying the properties of naturally occurring polyphenols. Regarding the preparation of acetyl esters, the presence of hydroxyl groups stabilized by intramolecular hydrogen bonds may pose an obstacle for the peracetylation of these compounds. In this paper, we present a facile protocol for the acetylation of selected polyphenols under mild reaction conditions by using acetic anhydride, catalytic amount 4-dimethylaminopyridine (DMAP) and dimethylformamide (DMF) as solvent. Reaction conditions were adjusted for optimal formation of peracetylated polyphenols while minimizing the formation of byproducts. Butyric anhydride was employed as an alternative acylating agent and showed similar results. Reaction yields varied from 78-97%, and products were obtained in high purity, as determined by LCMS(ESI+), 1H NMR and 13C NMR.
Keywords: Flavonoid; acylation; butyrilation; intramolecular hydrogen bond; xanthone.