I2/ionic liquid as a highly efficient catalyst for per-O-acetylation of sugar under microwave irradiation

A practical and highly efficient approach was developed to synthesize peracetylated sugar derivatives using a recyclable iodine/PEG400-based ionic liquid catalyst (I2/IL). The peracetylated sugars were readily obtained in a few minutes in excellent yields (90%–99%, 13 examples) on a multi-gram scale (50.0 mmol) by the reaction of sugar and acetic anhydride under microwave irradiation in the absence of a volatile organic solvent. The desired product was easily obtained by simple extraction with toluene from the reaction mixture, and I2/ILs can be readily recovered and reused at least six times without obvious loss in the yield. When the scale of the per-O-acetylation reaction was increased to 50.0 mmol, the desired product was still obtained in 90% yield after five recycles.