Proton and carbon chemical shift data and proton-proton coupling constants of the synthetic antithrombotic pentasaccharide SanOrg34006 and its synthetic precursors are reported. Long-range heteronuclear correlation experiments allow the determination of the substitution pattern of the protecting groups in the precursor molecules. Also, the sequence of the oligosaccharide was confirmed this way. The conformation of the a-L-iduronic acid moiety was studied by the analysis of the 3 J.