There are several biological events that are known to involve certain sulfated saccharides. In many such cases, however, clustered ligands have been shown to be more effective than monovalent saccharides. A set of 6-aminohexyl glycosides of 2,3,4 or 6-monosulfated galactose have been synthesized and linked to polyglutamic acid. Because of the bulky aglycon employed, the 2-OH group of the key compound, 6-benzyloxycarbonylaminohexyl 4,6-O-benzylidene-β-D-galactopyranosid was markedly less reactive than 3-OH. Thus, site-specific acetylation of 3-OH was readily carried out to obtain 2-O-sulfated galactosides, and even the direct sulfation of 3-OH afforded the 3-sulfate in a reasonable yield. On the other hand, the key compound was unexpectedly resistant to 2,3-O-dibenzylation or 2,3-O-dibenzoylation, both of which were meant for regioselective cleavage of 4,6-benzylidene to obtain the 4-sulfate.
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