Selective synthesis of 4,6-O-alkenylidene and -benzylidene acetals from unprotected sucrose by lanthanide(III) resin-catalyzed transacetalization

Lanthanide cation exchanged resins were used as catalysts for the acetaliza tion of sucrose. Ytterbium(III)- and erbium(III)-exchanged resins promote t he transacetalization of dialkyl acetals of alpha,beta-unsaturated aldehyde s. A two-step one-pot procedure provides direct access from the unsaturated aldehyde to a series of sucrose 4,6-acetals in good yields from unprotecte d sucrose without concomitant glycosidic bond cleavage.