Ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) could efficiently promote synthesis of a variety of 1,1-diacetates catalyzed by copper tetrafluoroborate from corresponding aromatic aldehydes and acetic anhydride at room temperature in 83%～97% yields for 3～20 min. The ac-tivity of the catalyst was shown to be much higher than that without ionic liquid in the same conditions. Use of only 0.2 mol% of the catalyst was sufficient to push the reaction forward and high amounts of the catalyst did not improve the yields to a great extent. The present protocol offered several advantages including low cost of the catalyst, high yields, short reaction time, simple work-up procedure, and moreover, the ionic liq-uid reusability and benignity to the environment.

Key words: ionic liquid, catalyze, 1,1-diacetate, copper tetrafluoroborate