Synthesis of the tetrasaccharide repeating-unit of the lipopolysaccharide isolated from Pseudomonas maltophilia.

The title tetrasaccharide having the structure 3-O-Me-beta-L-Xylp-(1----4)- alpha-L-Rhap-(1----4)-alpha-L-Rhap-(1----2)-L-Rhap was obtained by reaction of the alpha-acetobromo derivative of 4-O-(3-O-methyl-beta-L-xylopyranosyl)-L-rhamnopyranose and benzyl 3,4-di-O-benzyl-2-O-(2,3-O-isopropylidene-alpha-L-rhamnopyranosyl)- alpha-L-rhamnopyranoside, followed by removal of the protecting groups. The synthesised compounds were characterised on the basis of n.m.r. data.