Abstract
D-Mannose was treated with dry acetone in the presence of conc. H2SO4 to afford 2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranoside. Treating the latter with ethyl chloroacetate gave carboethoxymethyl 2,3:5,6-di-O-isopropylidene-alpha-D-mannofuranoside, which was hydrolyzed with N2H4 center dot H2O to afford the acid hydrazide derivative. Treating of the acid hydrazide with acylated amino acides, via the azide-coupling method afforded the corresponding O-glycopeptides. Reaction of the glycopeptide methyl esters with N2H4 center dot H2O afforded the corresponding hydrazides, which were coupled with the amino acid methyl esters to afford the dipeptides. Deprotection was carried out by using 70% AcOH. The prepared O-glycopeptides were tested for antiviral activity against hepatitis B virus and showed moderate activities.