Indium(III) Triflate: A Highly Efficient Catalyst for Reactions of Sugars[1]

Indium(III) trifluoromethanesulfonate has been found to be extremely efficient in catalyzing acyl transfer reactions of various carbohydrates and their derivatives. Selective acetolyses of certain benzyl ethers/isopropylidene acetals of sugars have been possible using In(OTf)3 in Ac2O (neat). Reaction of the per-O-acetate of 2-deoxy-2-phthalimido-D-glucose with benzyl mercaptan in the presence of In(OTf)3 led to the formation of the corresponding thioglycoside in high yield. Facile formation and hydrolysis of the isopropylidene and benzylidene acetals of various carbohydrates have also been achieved very efficiently in the presence of In(OTf)3. The results show great promise for In(OTf)3 in synthetic carbohydrate chemistry.