最新發表論文
Efficient Synthesis of p-Tolyl 6-Deoxy-d-Heptopyranose Thioglycosides

Capsular polysaccharides from a range of bacteria, notably campylobacters, possess 6-deoxy-heptose residues. Synthetic fragments of these polysaccharides have myriad applications in both fundamental and applied research, but few efficient routes for accessing these monosaccharides in a form suitable for glycosylation reactions are available. The synthesis of thioglycosides of 6-deoxy-d-manno-, 6-deoxy-d-talo-, and 6-deoxy-d-altro-heptoses from a single commercially available and inexpensive monosaccharide, methyl α-d-mannopyranoside, is reported here. The route involves C-6 homologation and, in some cases, configurational inversion at C-3 or C-4. These routes provide access to glycosyl donors of three of the four naturally occurring 6-deoxy-d-heptopyranoses, complementing previous work that has provided glycosyl donors of fourth such monosaccharide, 6-deoxy-d-ido-heptopyranose.