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 aC-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.