Regioselective acetylation of a tetrasaccharide has been accomplished using acetyl chloride and collidine in dichloromethane at low temp. The degree of acetylation depended on the time and equiv. of reagents used. However, only acetylation of primary positions was obsd. The acetylated oligosaccharides obtained after hydrogenolysis correspond to structures found in the capsular polysaccharide of Cryptococcus neoformans. The acetylation pattern in the target compds. was detd. both by NMR and methylation anal. [on SciFinder (R)]