An extremely efficient and green method for the acylation of secondary alcohols, phenols and naphthols with a deep eutectic solvent as the catalyst

The typical deep eutectic solvent [CholineCl][ZnCl2](3), easily prepared from choline chloride and zinc chloride, is green and useful for the acylation of secondary alcohols, phenols, and naphthols with acid anhydrides. Its efficiency allows the acylation of sterically hindered secondary alcohols and acid anhydrides to proceed in high yield under mild condition. The catalyst is cheap, easy to handle, conveniently synthesized in a single step, and recyclable for several times without significant loss of catalytic activity.