Y(OTf)3 as a highly efficient catalyst in Ferrier Rearrangement for the synthesis of O- and S-2,3-unsaturated glycopyranosides

By using Y(OTf)(3) as the catalyst, a series of 2,3-unsaturated-glucosides have been synthesized from 3,4,6-tri-O-acetyl-D-glucal, 3,4-di-O-acetyl-L-rhamnal, and 3,4,6-tri-O-benzyl-D-glucal under mild reaction conditions in good yields with high anomeric selectivities. It was found that, in this reaction, 3,4,6-tri-O-benzyl-D-glucal behaved differently from the other two glucals when it was reacted with phenol, O-benzyl glucoside instead of O-phenyl glucoside formed as the sole product. An explanation is given for this phenomenon. (C) 2014 Elsevier Ltd. All rights reserved.