A green and efficient method for regioselective O-acylation of polyphenols has been developed. The acylation can be carried out in potassiumcarbonate/dimethyl sulphoxide system by utilizing the ‘inherent nucleophile’ via an intermolecular cooperative transesterification under mild condition. This method shows particular advantage in regioselective acylation of polyphenols bearing 2′,4′-dihydroxyacetophenone