Synthesis of the hexasaccharide repeating unit corresponding to the cell wall lipopolysaccharide of Azospirillum irakense KBC1

A convenient chemical synthesis of the hexasaccharide repeating unit of the cell wall lipopolysaccharide of Azospirillum irakense KBC1 has been successfully achieved. A stereo- and regioselective [4 + 2] block glycosylation strategy has been used to obtain the target hexasaccharide as its octyl glycoside. All synthetic intermediates have been prepared in high yields from commercially available reducing sugars following a series of protection-deprotection reactions. An oxidation-reduction methodology has been applied to convert beta-D-glucosidic unit to a beta-D-mannosidic moiety. (C) 2010 Elsevier Ltd. All rights reserved.