Synthesis with glycosynthases: Cello-oligomers of isofagomine and a tetrahydrooxazine as cellulase inhibitors

Isofagomine and a carbohydrate-like tetrahydrooxazine, as their N-benzyloxycarbonyl derivatives, have been subjected to a glycosynthase in the presence of alpha-D-glucopyranosyl fluoride as a glucosyl donor. In each case, after protecting group removal, a mixture of 1, 4-beta-linked di-, tri-, and tetra-'saccharides' was obtained. These novel oligosaccharide derivatives were tested as inhibitors of the endo-glycanase Cex from Cellulomonas fimi. Affinities increased progressively as additional D-glucosyl residues were incorporated, which is consistent with the known substrate specificity of this enzyme.