SYNTHESIS OF ALLYL O-[SODIUM (ALPHA-D-GLYCERO-D-TALO-2-OCTULOPYRANOSYL)ONATE]-(2-]6)-2-ACETAMIDO-2-DEOXY-BETA-D-GLUCOPYRANOSIDE, A CORE CONSTITUENT OF THE LIPOPOLYSACCHARIDE FROM ACINETOBACTER-CALCOACETICUS NCTC 10305

Reaction of methyl 2,6-anhydro-2,3-dideoxy-D-manno-2-octenoate 1 with 3-chloroperoxybenzoic acid gave the 2,3-anhydro derivative 2, which was converted into the per-O-acetylated anomeric methyl glycosides of D-glycero-D-galacto-2-octulopyranosylonic acid in good yield. Subsequent inversion of the configuration at C-3 and deprotection afforded sodium (methyl beta-D-glycero-D-talo-2-octulopyranosid)onate. Alternatively, 2 was transformed into methyl (alpha-D-glycero-D-talo-2-oc-tulopyranosyl bromide)onate derivatives. Reaction with methanol or allyl 2-acetamido-2-deoxy-3,4-O-(1,1,3,3-tetraisopropyldisiloxan-1,3-diyl)-beta-D-glycopyranoside, promoted by silver triflate, gave good yields of the corresponding orthoester derivatives. Me3Si triflate-catalyzed orthoester rearrangement and removal of the protecting groups afforded sodium O-(methyl alpha-D-glycero-D-talo-2-octulopyranosid)onate and the disacchanide, allyl O-[sodium (alpha-D-glycero-D-talo-2-octulopyranosyl)-onate]-(2 --> 6)-2-acetamido-2-deoxy-beta-D-glucopyranoside in high yield.