Reaction of methyl 2,3,4-tri-O-acetyl-beta-D-glucuronyl-3-nitrobenzyl alcohol (I) with N,N'-disuccinimidyl carbonate affords the mixed carbonate ester (II), which is further coupled to glycine (III), producing carbamate (IV). Alcoholysis of (IV) with NaOMe in MeOH yields the deacetylated conjugate (V). This is then activated as the pentafluorophenyl ester (VI) upon treatment with pentafluorophenol and DCC.

Coupling between N-Boc-O-benzyl-L-threonine (VII) and L-leucine benzyl ester (VIII) by means of DCC/HOBt gives the protected dipeptide (IX). Subsequent N-Boc group cleavage in (IX) upon treatment with formic acid yields (X). Further coupling of dipeptide (X) with N-Boc-L-phenylalanine (XI), followed by formic acid deprotection, leads to the benzyl-protected tripeptide (XII).

In a similar fashion, N-Boc-L-phenylalanine (XI) is coupled with L-valine benzyl ester (XIII) to furnish the protected dipeptide (XIV). Debenzylation of (XIV) with H2 and Pd/C leads to acid (XV), which is then condensed with tripeptide (XII) to yield, after deprotection with formic acid, the pentapeptide derivative (XVI).

Coupling of N-Boc-L-leucine (XVII) with glycine benzyl ester (XVIII), followed by acidic N-Boc group cleavage, affords the dipeptide benzyl ester (XIX), which is submitted to coupling with N-Boc-L-isoleucine (XX) and further benzyl ester hydrogenolysis to give rise to the N-Boc tripeptide (XXI). Then, assembly between (XXI) and pentapeptide (XVI) is accomplished by means of EDC/HOBt, providing the protected peptide (XXII). Hydrogenolysis of the benzyl groups of (XXII), followed by Boc group cleavage with trifluoroacetic acid, leads to the fully deprotected octapeptide (XXIII).

Condensation of pentafluorophenyl ester (VI) with octapeptide (XXIII) gives rise to the nonapeptide conjugate (XXIV). The methyl ester group of (XXIV) is finally hydrolyzed by means of barium hydroxide in MeOH to produce the target compound.