Synthesis of neoglycoproteins containing D-glycero-D-talo-oct-2-ulopyranosylonic acid (Ko) ligands corresponding to core units from Burkholderia and Acinetobacter lipopolysaccharide

摘要

Glycal esters of Kdo derivatives were converted into 2,3-anhydro intermediates, which were transformed into D-glycero-D-talo-oct-2-ulopyranosylonic acid (Ko), as well as 3-O- and 4-O-p-nitrobenzoyl-Ko derivatives. The exo-allyl orthoester derivative, methyl {5,7,8-tri-O-acetyl-4-O-(4-nitrobenzoyl)-2,3-O-[(1-exo-allyloxy)-ethyliden e]-D-glycero-beta -D-talo-oct-2-ulopyranos}onate, prepared from the 4-O-pNBz-protected Ko derivative, was elaborated into the alpha -Ko allyl ketoside, the reducing disaccharide alpha -Kdop-(2 --> 4)-Ko and the disaccharide alpha -Kdop-(2 --> 4)-Kop-(2 -->, OAll). Conversely, methyl[4, 5,7,8-tetra-O-acetyl-3-O-(4-nitrobenzoyl)-alpha -D-glycero-D-talo-2-octulopyranosyl bromide]onate [Carbohydr. Res., 244 (1993) 69-84], was coupled with a Kdo acceptor to give the disaccharide alpha -Kop-(2 -->4)-Kdop-(2 --> OAll) after orthoester rearrangement and deprotection. The allyl glycosides were treated with cysteamine and converted into neoglycoproteins. The ligands correspond to inner core units from Acinetobacter haemolyticus and Burkholderia cepacia lipopolysaccharides. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 22]