The goal is the discovery and refinement of new approaches to the synthesis of biologically important carbohydrates. The ability to synthesize carbohydrate components of antibiotics and antitumor agents is an important part of analog development since modification of the sugar residue may provide compounds exhibiting different activity. The proposed synthesis of the branched-chain monosaccharides vine-lose 1, kansosamine 2, and sibirosamine 3 are described. Both 1 and 2 are components of bacterial lipopolysaccharides and 3 occurs in the antitumor antibiotic sibiromycin. These carbohydrates contain a geminally substituted carbon which bears methyl and hydroxyl groups. The introduction of these groups with the correct stereochemistry, the most critical part of the synthetic strategy for this class of compounds, is achieved by the addition of a Grignard reagent to a keto sugar in its furanose form. If successful, the route proposed will provide compounds 1, 2, and 3 from a single intermediate in high stereoselectivity. The proposed synthesis of the trisaccharide moiety of the anthracycline antibiotic arugomycin is described. Derivatives of L-decilonitrose, an unusual branched-chain nitro sugar present in the trisaccharide, will be investigated as donors in the glycosylation of the 2-deoxy-L-fucosyl residue. Neighboring group participation in these derivatives may lead not only to a highly stereoselective glycoside synthesis but also to new methods for the glycosylation of other branched-chain, deoxy, and amino sugars.
NIH ExPorter
NIH ExPorter