synthesis of 2,3-unsaturated furanic hex- and pent-enopyranoside employing the ferrier rearrangement

Glycosidation of various glycals with furanic alcohols in presence of catalytic amount of ceric(IV) ammonium nitrate under neutral condition or using Lewis acid-catalysed proceeds smoothly to afford the corresponding 2,3-unsaturated glycosides in good yields. In the hexose series predominantly α-D-anomers resulted while β-D-anomers are predominant in the pentose serie.