Synthesis of the pentasaccharide repeating unit of the O-antigen from Enterobacter cloacae C4115 containing the rare α-d-FucNAc

Abstract

Pentasaccharide repeating unit of the O-antigen of Enterobacter cloacae C4115 is accomplished through rational protecting group manipulations. For the synthesis of α-d-FucNAc, it was established that the methoxymethyl (MOM) group is advantageous over the earlier reported tetrahydro pyran (THP) protection.

Thiourea-Cu(OTf)2/NIS-synergistically promoted stereoselective glycoside formation with 2-azidoselenoglycosides or thioglycosides as donors

“…2-Acetamido-2-deoxy- d -fucose ( d -FucNAc) is another representative 2,6-dideoxysaccharide unit that is often found in bacterial capsular polysaccharide, which is associated closely with pediatric pneumonia. 21 The efficacy of the method was further explored with the d -fucoazide donor D6 , which was derived from d -galactal and structurally characterized as an enantiomer of D5 . The reactions of pyranose and furanose acceptors with a sterically hindered secondary hydroxyl group at the 2-, 3-, or 4-position gave the corresponding disaccharides G22–G24 with α/β ratios > 30 : 1 and moderate 51–62% yields.…”