The synthesis of a linear hexasaccharide, 2-(4-trifluoroacetamidophenyl)ethyl (b-D-galactopyranosyl)-(1->4)-(2-acetamido-2-deoxy-b-D-glucopyranosyl)-(1->3)-(b-D-galactopyranosyl)-(1->4)-(D-glycero-a-D-manno-heptopyranosyl)-(1->6)-(b-D-glucopyranosyl)-(1->4)-L-glycero-a-D-manno-heptopyranoside, corresponding to a structure found in Haemophilus ducreyi LPS, is described. A Barbier reaction between benzyloxymethyl chloride and a properly protected 6-aldo-1-thio-mannopyranoside yielded both the D,D- and the L,D-heptopyranoside, which were sepd. and both used in the synthesis. P-Methoxybenzyl and chloroacetyl groups were employed as temporary protecting groups, selectively removed in the presence of the persistent benzyl, acetyl, benzoyl and isopropylidene groups by treatment with DDQ/H2O and hydrazine dithiocarbonate, resp. Thioglycosides were utilized as donors throughout using either NIS/TfOH or DMTST as promoters. The introduction of the spacer into thioglycoside I was high-yielding (95%) but with low stereoselectivity (a:b 5:3). All other glycosylations are completely stereoselective. The target hexasaccharide is obtained via a 3+3 block approach with the yield in the final NIS/TfOH-promoted coupling between an N,N-diacetyl-trisaccharide thioglycosyl donor and a 4\"-OH trisaccharide acceptor being 75%. [on SciFinder (R)]