Stereoselective Synthesis of α-3-Deoxy-<scp>D</scp>-<i>manno</i>-oct-2-ulosonic Acid (α-Kdo) Glycosides Using 5,7-<i>O</i>-Di-<i>tert</i>-butylsilylene-Protected Kdo Ethyl Thioglycoside Donors
作者:Jia-Sheng Huang、Wei Huang、Xue Meng、Xin Wang、Peng-Cheng Gao、Jin-Song Yang
DOI:10.1002/anie.201505176
日期:2015.9.7
for the synthesis of α‐Kdo glycosidic bonds has been developed with 5,7‐O‐di‐tert‐butylsilylene (DTBS) protected Kdoethylthioglycosides as glycosyl donors. The approach permits a wide scope of acceptors to be used, thus affording biologically significant Kdoglycosides in good to excellent chemical yields with complete α‐selectivity. The synthetic utility of an orthogonally protected Kdodonor has been
The disaccharides O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2 --> 8)-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (8), O-L-glycero-alpha-D-Manno-heptopyranosyl-(l --> 7)-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (12), and 0-alpha-D-mannopyranosyl-(1 --> 7)-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (21) and the branched trisaccharides O-L-glycero-alpha-D-manno-heptopyranosyl-(l --> 7)-[O-(sodium 3-deoXy-alpha- and -beta-D-manno-2-octulopyranosylonate)-(2 --> 8)]-sodium (allyl 3-deoXY-beta-D-manno-2-octulopyranosid)onate (15 and 16) and 0-alpha-D-mannopyranosyl-(1 --> 7)-[O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2 --> 8)]-sodium (allyl 3-deoxy-beta-D-manno-2-octulopyranosid)onate (24) were prepared. Per-O-acetylated mannopyranosyl or Kdo bromide derivatives were employed for the glycosylation steps under Helferich conditions, whereas the imidate derivative 9 was used for the coupling of the L-glycero-D-manno-heptopyranosyl residues. The oligosaccharides were fully characterized by NMR spectroscopic data. Their structures correspond to an artificial linkage pattern providing a potential cross-reactive epitope for antibodies directed against the inner-core-region of enterobacterial as well as chlamydial lipopolysaccharides.