Synthesis of Fondaparinux: modular synthesis investigation for heparin synthesis

The anti-thromboembolic pentasaccharide Fondaparinux was synthesized in 36 steps for the longest linear route, with 0.017% overall yield from d-glucose. Only three kinds of protecting groups were used for hydroxyl protection, Bn, Ac, and Bz, to accomplish this complex synthesis without decreasing the synthetic efficiency. Three l-idopyranosyl donors were investigated. Thioethyl glycoside is an efficient donor for l-idopyranosyl glycosylation with full α-selectivity, while l-idopyranosyl trichloroacetimidate resulted in poor α/β selectivity. A practical synthesis of key intermediate 1,6-anhydro-l-idopyranose 17 by H+/β-CD catalyst was developed.

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