Enzymatic glycosidation of sugar oxazolines having a carboxylate group catalyzed by chitinase Original Research Article

Enzymatic glycosidation using sugar oxazolines 1–3 having a carboxylate group as glycosyl donors and compounds 4–6 as glycosyl acceptors was performed by employing a chitinase from Bacillus sp. as catalyst. All the glycosidations proceeded with full control in stereochemistry at the anomeric carbon of the donor and regio-selectivity of the acceptor. The N,N′-diacetyl-6′-O-carboxymethylchitobiose oxazoline derivative 1 was effectively glycosidated, under catalysis by the enzyme, with methyl N,N′-diacetyl-β-chitobioside (4), pent-4-enyl N-acetyl-β-d-glucosaminide (5), and methyl N-acetyl-β-d-glucosaminide (6), affording in good yields the corresponding oligosaccharide derivatives having 6-O-carboxymethyl group at the nonreducing GlcNAc residue. The N,N′-diacetyl-6-O-carboxymethylchitobiose oxazoline derivative 2 was subjected to catalysis by the enzyme catalysis; however, no glycosidated products were produced through the reactions with 4, 5, and 6. Glycosidation reactions of the β-d-glucosyluronic-(1→4)-N-acetyl-d-glucosamine oxazoline derivative 3 proceeded with each of the glycosyl acceptors, giving rise to the corresponding oligosaccharide derivative having a GlcA residue at their nonreducing termini in good yields.