An improved synthesis of propyl 4-O-(3,6-di-O-methyl- beta-D-glucopyranosyl)-2,3-di-O-methyl-alpha-L-rhamnopyranoside, a disaccharide corresponding to the phenolicglycolipid of Mycobacteriumleprae using a trichloroacetimidate as a glycosyl donor is described. The synthetic strategy is also applied to the preparation of three corresponding disaccharide analogues containing 13C-labeled methyl groups