Glucosamine derivatives, disaccharide

Thus, the O-benzylated glucosamine derivative 60 was condensed with the spacer-linked L-rhamnoside 61, followed by the removal of the base-labile protecting group at the site of the chain extension to afford the disaccharide acceptor 62. The trisaccharide block 67 was prepared in a similar approach. Thus, condensation of the glucosamine derivative 63 with rhamnoside 64 afforded the disaccharide... 

The glucosamine derivative (36) has been used to prepare lipid X (37), the Salmonella lipid A precursor, A variety of mono- and disaccharide analogues of lipid A have been prepared -1 phosphoryl-... 

Discussion of the use of the Tebbe reagent for the synthesis of methylene sugars from which -linked disaccharides can be prepared is contained in a review of some Du Pont research. In related work, the -methyl a-D-glucosamine derivative (76) was obtained, together with minor proportions of the /9-anomer, by use of vinylmagnesium bromide (Scheme 36), but... 

The chemistry and biological activities of lipid A are reviewed in earlier chapters of this volume. As noted there, the components of the lipid A complexes from Salmonella species and j5. coli are derivatives of a disaccharide comprised of two D-glucosamine units linked B,l->-6. The disaccharide is substituted at positions 1 and 4 by phosphate functions and on the amino nitrogens by B-hydroxymyristoyl groups. A variable number (up to 5) of ester-linked fatty acyl residues is also present. In the simplest components the phosphates are present as monoester groups. 

---