Synthesis of 2,5-anhydro-(β-d-glucopyranosyluronate)- and (α-l-idopyranosyluronate)-d-mannitol hexa-O-sulfonate hepta sodium salt

Glycosidation of 2,5-anhydro-1,6-di-O-benzoyl-d-mannitol with methyl(2,3,4-tri-O-acetyl-α-d-glucopyranosyl-1-O-trichloroacetimidate)uronate in the presence of trimethylsilyl triflate afforded the corresponding 3-O-β-glycoside, which after deprotection was converted into its hexa-O-sulfate with DMF·SO3 to give after treatment with sodium acetate and subsequent saponification of the methyl ester with sodium hydroxide the hepta sodium salt of 2,5-anhydro-3-O-(β-d-glucopyranosyl uronate)-d-mannitol hexa-O-sulfate. Glycosidation of the same acceptor with the α-thiophenylglycoside of methyl 2,4-di-O-acetyl-3-O-benzyl-l-idopyranosyl uronate in the presence of NIS/TfOH afforded the corresponding 3-O-α-glycoside in very low yield, therefore the α-thiophenylglycoside of 2-O-acetyl-2,4-O-benzylidene-3-O-benzyl-l-idopyranose was used as donor. The terminal hydroxymethyl group of the obtained disaccharide was subsequently oxidised with NaOCl/TEMPO and the obtained iduronic acid derivative was converted into the hepta sodium salt of 2,5-anhydro-3-O-(-α-l-idopyranosyluronate)-d-mannitol hexa-O-sulfonate with DMF·SO3 and subsequent treatment with sodium acetate.