The donor, 3,4,6-tri-O-acetyl-2-deoxy-2-(2,2,2-trichloroethoxy)carbonylamino-α-D-glucopyranosyl trichloroacetimidate (5), and the acceptor, allyl 4,6-O-benzylidene-2-deoxy-2-(2,2,2-trichloroethoxy)~carbonyl~amino-α-D-glucopyranoside (7), were prepared from D-glucosamine hydrochloride. Trichloroethoxycarbonyl group was used as an amino protecting group and trichloroacetimidate was used as aleaving group. Reaction of 5 with glycosylacceptor 7 in the presence of trimethylsilyl trifluoromethanesulfonateafforded the fully protected disaccharide allyl 3,4,6-tri-O-acetyl-2-deoxy-2-(2,2,2-trichloroethoxy)carbonylamino-β-D-glucopyranosyl-(1→3)-4,6-O-benzyl~idene-2-deoxy-2-(2,2,2-trichloroethoxy)carbonylamino-α-D-glucopyranoside (10) in yield of 39.2%. When 7 was treated with barium oxide, barium hydroxide octahydrate and benzyl bromide to realize benzylation at its 3-position, the unexpected product, allyl-3-O-benzyl-4,6-O-benzylidene-2-deoxy-2-hydroxy-carbonylamino-α-D-glucopyranoside (8), was obtained. But allyl-3-O-benzyl-4,6-O-benzylidene-2-deoxy-2-(2,2,2-trichloroethoxy)carbonylamino-α-D-glucopyranoside (9) was obtained smoothly without cleavage of the N-Troc in the benzylation of 3-hydroxyl group of 7 with BnBr in the presence of Ag₂O. The title compound 10 has the moderate fungicidal activity to Bacillus subtilis and Rhizopus stolonifer et.

Key words: 2-amino-2-deoxy-glucose, glycoside, benzylation