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%.