Synthesis of di-and tetrasaccharide containing 6-deoxytalose from the O-antigenic polysaccharide of B. pseudomallei strain 304b

Synthesis of the disaccharide [3-D-Glup-（1→3）-6-deoxy-α-L-Talp Ⅱ, and its dimer Ⅲ from the O-antigenic polysaccharide of Burkholderia pseudomallei strain 304b, were achieved through assembly of suitably synthesized building blocks, 4-methox- ylphenyl 6-deoxy-2,4-di-O-benzoyl-α-L-talopyranoside （7）, 3-O-allyl-2,4,6-tri-O-benzoyl-α,β-D-glucopyranosyl trichloroacetimi- date （8） and 2,3,4,6-tetra-O-benzoyl-α,β-D-glucopyranosyl trichloroacetimidate （11）. The total yield of Ⅲ from 4-methoxylphenyl 2.3-O-isopropvlidene-α-L-rhamnoovranoside （1） was 18%.

Synthesis of macrocyclic lactones with methoxysulfonyl side chain

Two representative macrocyclic lactones with methoxysulfonyl side chain（5a and 5b）were synthesized employing Michael addition with acrolein and ring enlargement as the key steps,starting from potassium,α-oxocycloaikylsulfonates（1）in total yields of 45 and 57%,respectively.

Synthesis of 12-alkoxycarbonylmethylene-1,15-pentadecanolides

Six novel 12-alkoxycarbonylmethylene-1,15-pentadecanolides （3） were synthesized from 2-nitrocyclo-dodecanone by the Michael addition with acrolein followed by ring enlargement, Nef reaction and Wittig-Homer reaction. Their structures were confirmed bv 1H NMR, IR and elemental analysis. The preliminary bioassay showed that they have some fungicidal activity.

Synthesis ofα-D-GlcpNAc-(1→2)-[α-D-ManpNAc-(1→3)-]α-L-Rhap-(1→2)-α-L-Rhap-(1→3)-α-L-Rhap,the repeating unit of O10 antigen from Acinetobacter baumannii

An efficient synthesis ofα-D-GlcpNAc-（1→2）-[α-D-ManpNAc-（1→3）-]α-L-Rhap-（1→2）-α-L-Rhap-（1→3）-α-L-Rhap（1）, the repeating unit of the O10 antigen from Acinetobacter baumannii was achieved via sequential assembly of the building blocks,p- methoxylphenyl 2,4-di-O-benzoyl-α-L-rhamnopyranoside（2）;2-O-allyloxycarbonyl-3,4-di-O-bcnzoyl-α-L-rhamnopyranosyl tri- chloroacetimidate（3）;4-methoxylphenyl 3-O-allyloxycarbonyl-4-O-benzoyl-α-L-rhanmopyranoside（4）;2-azido-3-O-benzoyl-2- deoxy-4,6-O-isopropylidene-α-D-mannopyranosyl trichloroacetirnidatc（5）;2-azido-3,4,6-tri-O-benzoyl-2-deoxy-α,β-D-glucopyr- ano syl trichloroacetimidatc（6）.The total yield of 1 from 4 was 4.7%.

Highly efficient removal of allyloxycarbonyl(Alloc)function provides a practical orthogonal protective strategy for carbohydrates

Highly efficient removal of allyloxycarbonyl （Alloc） group was achieved in the presence of CH3COONH4, Pd[P（C6H5）3]4, and NaBH4 in MeOH-THF, within 5 min in almost quantitative yields （〉90%, isolated yield） without affecting acetyl, benzoyl, isopropylidene, benzylidene, allyl, benzyl, benzyl carbonate, or azido groups.