A highly efficient TMSOTf-catalyzed HMDS silylation of sugars, which can easily be integrated with subsequent reactions in one-pot fashion, has been developed. Its usefulness was demonstrated by applications to streamlined regioselective one-pot protection and nonenzymatic acetylation of un-

Sulfation on the glucosamine sugar unit in heparan sulfate (HS) is linked to various biological functions, including the anticoagulant activity to treat thrombotic disorders in hospitals. The 3-O-sulfated glucosamine is biosynthesized by heparan sulfate glucosamine 3-sulfotransferases. Because of its biological significance, there is a need for 3-O-sulfated oligosaccharide standards to facilitate the compositional analysis of HS. These oligosaccharides must contain a Δ 4,5 -unsaturated uronic acid (ΔUA) residue at the nonreducing end, which is due to the depolymerization reaction catalyzed by heparin lyases used during the compositional analysis procedure. Here, we describe a protocol for the preparation of one 3-O-sulfated disaccharide (compound 4) and three 3-Osulfated tetrasaccharides (compound 1−3) in a milligram scale. The synthesis of 3-O-sulfated disaccharide and tetrasaccharide standards was completed by degrading synthetic octasaccharides using heparin lyases. Further analysis revealed that 3-O-sulfated oligosaccharide standards are labile under basic conditions, confirming the findings from a previous study. The unwanted degradation was reduced by decreasing the pH in the presence of phosphate buffer. The 3-O-sulfated oligosaccharide standards are reagents to characterize 3-O-sulfation in HS derived from biological sources.

Living organisms employ glycans as recognition elements because of their large structural information density. Well-defined sugar structures are needed to fully understand and take advantage of glycan functions, but sufficient quantities of these compounds cannot be readily obtained from natural sources and have to be synthesized. Among the bottlenecks in the chemical synthesis of complex glycans is the preparation of suitably protected monosaccharide building blocks. Thus, easy, rapid, and efficient methods for building-block acquisition are desirable. Herein, we describe routes directly starting from the free sugars toward notable monosaccharide derivatives through microwave-assisted one-pot synthesis. The procedure followed the in situ generation of per-O-trimethylsilylated monosaccharide intermediates, which provided 1,6-anhydrosugars or thioglycosides upon treatment with either trimethylsilyl trifluoromethanesulfonate or trimethyl(4-methylphenylthio)silane and ZnI2, respectively, under microwave irradiation. We successfully extended the methodology to regioselective protecting group installation and manipulation toward a number of thioglucosides and the glycosylation of persilylated derivatives, all of which were conducted in a single vessel. These developed approaches open the possibility for generating arrays of suitably protected building blocks for oligosaccharide assembly in a short period with minimal number of purification stages.

A highly efficient CH3CN-promoted hexamethyldisilazane per-O-trimethylsilylation of amino sugars was developed. Its applications in homogenous N-functionalisation and a concise synthesis of glucosamine 6-phosphate are described.