A Facile Synthesis of 4-Methylumbelliferyl (1→3)-β-D-Pentaglucoside

The synthesis and stability assay of 4-methylumbelliferyl (1→3)-β-D-pentaglucoside 3 are described. The acid-solubilized (1→3)-β-D-oligoglucosides were prepared by partial acid hydrolysis of glucan. The peracetylated (1→3)-β-D-pentaglucoside 1 was obtained by isolation of peracetylated (1→3)-β-D-oligoglucoside mixture. The peracetylated 4-methylumbelliferyl (1→3)-β-D-pentaglucoside 2 was synthesized by treating compound 1 with the 4-methylumbelliferone and a Lewis acid (SnCl4) catalyst. NaOMe in dry methanol was used for the deacetylation of the blocked derivative, to give the target compound 3 in an overall yield of 35%. In the activity assays of fungal β-glucosidase, it indicates that compound 3 is much more stable than the corresponding pentasaccharide.