Synthesis of a Lipodisaccharidic Reagent for the Chemical Modification of Enzymes

ABSTRACT

The preparation of an amphiphilic lipodigalactosyl hemiacetal is described. Use of benzoyl protecting groups and mild conditions for detritylation allow preparation of a 1-α-C-allyl galactosyl acceptor without intramolecular acyl transfer. Condensation with a lipogalactosyl donor and cleavage of the protecting groups gave a C-allyl disaccharide. Reductive ozonolysis of the double bond yielded an aldehyde which spontaneously formed a cyclic hemiacetal with the C-2 hydroxyl group. In the Lewis acid catalyzed allylation of the penta-O-acetyl galactose with allyltrimethylsilane, the reactivity of the β-anomer is much higher than that of the α-anomer.