In the Gram-negative bacterial cell wall α-Kdo is an important component of the inner core region of lipopolysaccharide (LPS), which is frequently recognized by lectins and antibodies of the immune system in hosts.[1] Chemical glycosylation using Kdo donors, however, is typically hampered by the lack of a stereodirecting group at C-3, their propensity towards elimination reactions and the low intrinsic reactivity due to the deactivating C-1 ester. In this contribution, the application of easily accessible 3-iodo Kdo fluoride donors (Scheme 1) on the efficient assembly of LPS fragments of the Chlamydiaceae family and the Acinetobacter species – the latter one being responsible for severe nosocomical infections – will be presented. Notably, these glycosylations are highly α-selective and elimination reactions are largely suppressed affording good to high isolated yields (58 to 83%) of the exclusively α-linked products. Capitalizing on a mild hydrogen atom transfer reaction[2] the auxiliary group is subsequently removed cleanly. Sequential iteration of the basic concept allows for linear oligosaccharide synthesis. [1] Weis W.I., et al.; Immunol. Rev. 1998, 163, 19 – 34 [2] Boivin J., et al.; Chem. Commun. 1997, 4, 353-354 Financial support from the Austrian Science Fund (FWF) is gratefully acknowledged (P24921-N28).

Efficient and α-selective glycosylation using 3-iodo Kdo (3-deoxy-D-manno-oct-2-ulosonic acid) fluoride donors

249th National Meeting (2015)

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