Regioselectivity in acid- or base-catalysed acetalation of sucrose: selection of [OH-2, OH-3] or [OH-4, OH-6] diols

Regioselective monoacetalation of sucrose can be achieved without prior pro tection. Under acidic catalysis, and notably with the use of lanthanide-exc hanged cation resins as heterogeneous catalysts, sucrose monoacetals of alp ha,beta-unsaturated carbonyl compounds involving OH-4 and OH-6 are obtained . On the other hand, the reaction of unprotected sucrose with a alpha-chlor omethyl ketone in the presence of base provided a alpha-hydroxymethyl 5-mem bered ring acetal involving OH-2 and OH-3 as the major product, illustratin g the pre-eminent reactivity of OH-2 in sucrose and its consequences on the product distribution for reactions under kinetic control.