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[摘要]：Methyl 4-azido-4-deoxy-beta-L-arabinopyranoside has been synthesized in five steps starting from methyl beta-D-xylopyranoside in a multigram scale without chromatographic purification in 78% overall yield. The transformation relied on selective tosylation/nosylation at O-4 followed by acylation, S(N)2 displacement with sodium azide, and subsequent deprotection. The methyl 4-azido-4-deoxy-arabinoside was then converted into allyl, propenyl, omega-bromohexyl, and chloroethoxyethyl spacer glycosides by transglycosylation with the respective alcohols in good yields and fair anomeric selectivity. Reduction of the azido group and further transformations of the aglycone afforded omega-thiol-containing spacer derivatives. Coupling to maleimide-activated BSA provided a potent immunogen, which was used to generate murine and rabbit polyclonal sera binding to LPS-core epitopes containing 4-amino-4-deoxy-arabinose residues. |
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