Synthesis of α-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 of α-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-benzoyl-α-L-rhanmopyranosyl trichloroacetimidate (3);4-methoxylphenyl 3-O-allyloxycarbonyl-4-O-benzoyl-α-L-rhamnopyranoside (4);2-azido-3-O-benzoyl-2-deoxy-4, 6-O-isopropylidene-α-D-mannopyranosyl trichloroacetimidate (5);2-azido-3, 4, 6-tri-O-benzoyl-2-deoxy-α, β-D-glucopyrano syl trichloroacetimidate (6).The total yield of 1 from 4 was 4.7%.