Condensation of S-(4-monomethoxytrityl)-L-cysteine (I) with 2-naphthalenesulfonyl chloride (II) under Schotten-Baumann conditions afforded sulfonamide (III). Cleavage of the trityl group of (III) by treatment with trifluoroacetic acid and triisopropylsilane gave thiol (IV), which was protected as the thiopyridyl derivative (V) using dithiodipyridine. Coupling of (V) with 4-amidinophenylalanyl piperidine (VI) by means of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide - HCl (EDC), 1-hydroxybenzotriazole (HOBt) and N-ethylmorpholine (NEM) furnished dipeptide (VII). The thiopyridyl group of (VII) was then deprotected by treatment with tributyl phosphine to afford thiol (VIII).

The known pentasaccharide (IX) was reacted with N-(benzyloxycarbonyl)succinimide (X) yielding carbamate (XI). Sulfation of the free hydroxyl groups of (XI) with triethylamine-sulfur trioxide complex gave the sulfated compound which, after acid cleavage of the formed N-SO3- groups, was converted to the corresponding sodium salt (XII). Hydrogenolysis of the N-benzyloxycarbonyl group then liberated amine (XIII).

Amine (XIII) was coupled with the 4-(iodoacetamido)benzoic acid active ester (XIV) to produce amide (XV).

Displacement of the iodide of (XV) by thiol (VIII) gave rise to the title sulfide derivative.

Condensation of S-(4-monomethoxytrityl)-L-cysteine (I) with 2-naphthalenesulfonyl chloride (II) under Schotten-Baumann conditions afforded sulfonamide (III). Cleavage of the trityl group of (III) by treatment with trifluoroacetic acid and triisopropylsilane gave thiol (IV), which was protected as the thiopyridyl derivative (V) using dithiodipyridine. Coupling of (V) with 4-amidinophenylalanyl piperidine (VI) by means of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide - HCl (EDC), 1-hydroxybenzotriazole (HOBt) and N-ethylmorpholine (NEM) furnished dipeptide (VII). The thiopyridyl group of (VII) was then deprotected by treatment with tributyl phosphine to afford thiol (VIII).

The known pentasaccharide (IX) was reacted with N-(benzyloxycarbonyl)succinimide (X) yielding carbamate (XI). Sulfation of the free hydroxyl groups of (XI) with triethylamine-sulfur trioxide complex gave the sulfated compound which, after acid cleavage of the formed N-SO3- groups, was converted to the corresponding sodium salt (XII). Hydrogenolysis of the N-benzyloxycarbonyl group then liberated amine (XIII).

Amine (XIII) was coupled with the 4-(iodoacetamido)benzoic acid active ester (XIV) to produce amide (XV).

Displacement of the iodide of (XV) by thiol (VIII) gave rise to the title sulfide derivative.