SYNTHESIS OF HEPARIN FRAGMENTS. A CHEMICAL SYNTHESIS OF THE TRISACCHARIDE O-(2-DEOXY-2-SULFAMIDO-3,6-DI-O-SULFO-α-D-GLUCOPYRANOSYL)-(1->4)-O-(2-O-SULFO-α-L-IDOPYRANOSYL-URONIC ACID)-(1->4)-2-DEOXY-2-SULFAMIDO-6-O-SULFO-D-GLUCOPYRANOSE HEPTASODIUM SALT

Article abstract of DOI:10.1016/0008-6215(84)85281-7

Known 3-O-benzyl-1,2-O-isopropylidene-α-D-glucofuranose was first converted into methyl 3-O-benzyl-1,2-O-isopropylidene-β-L-idofuranuronate.Acid hydrolysis, followed by acetylation and treatment with titanium tetrabromide, gave methyl (2,4-di-O-acetyl-3-O-benzyl-α-L-idopyranosyl bromide)uronate, which was immediately transformed into methyl 4-O-acetyl-3-O-benzyl-β-L-idopyranuronate 1,2-(tert-butyl orthoacetate).A two-step replacement of the 4-O-acetyl by a 4-O-chloroacetyl group gave the key derivative, crystalline methyl 3-O-benzyl-4-O-chloroacetyl-β-L-idopyranuronate 1,2-(tert-butyl orthoacetate).Condensation of this orthoester with an excess of crystalline benzyl 6-O-acetyl-3-O-benzyl-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside in chlorobenzene in the presence of 2,6-dimethylpyridinium perchlorate gave crystalline benzyl 6-O-acetyl-3-O-benzyl-2-(benzyloxycarbonyl)amino-2-deoxy-4-O-(methyl 2-O-acetyl-3-O-benzyl-4-O-chloroacetyl-α-L-idopyranosyluronate)-α-D-glucopyranoside in 40 percent yield.O-Demonochloroacetylation, followed by condensation with known 3,6-di-O-acetyl-2-azido-4-O-benzyl-2-deoxy-α-D-glucopyranosyl bromide in dichloromethane in the presence of 2,4,6-trimethylpyridine, silver triflate, and molecular sieve provided benzyl O-(3,6-di-O-acetyl-2-azido-4-O-benzyl-2-deoxy-α-D-glucopyranosyl)-(1->4)-O-(methyl 2-O-acetyl-3-O-benzyl-α-L-idopyranosyluronate)-(1->4)-6-O-acetyl-3-O-benzyl-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside in 88 percent yield.O-Deacetylation with sodium hydroxide, followed successively by O-sulfation in N,N-dimethylformamide in the presence of sulfur trioxide-trimethylamine complex, catalytic hydrogenolysis, and N-sulfation in water with the same sulfating agent, gave the heptasodium salt of O-(2-deoxy-2-sulfamido-3,6-di-O-sulfo-α-D-glucopyranosyl)-(1->4)-O-(2-O-sulfo-α-L-idopyranosyluronic acid)-(1->4)-2-deoxy-2-sulfamido-6-O-sulfo-D-glucopyranose.This trisaccharide, which is a fragment of the minimal antithrombin III-binding region in heparin, neither binds to antithrombin III nor induces anti-Xa activity.