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. 2016 May 11;21(5):614.
doi: 10.3390/molecules21050614.

Efficient Synthesis of the Lewis A Tandem Repeat

Daisuke Kobayashi  1 , Akiharu Ueki  2   3   4 , Tomoya Yamaji  5 , Kazuya Nagao  6 , Akihiro Imamura  7 , Hiromune Ando  8   9 , Makoto Kiso  10   11 , Hideharu Ishida  12
Affiliations

Efficient Synthesis of the Lewis A Tandem Repeat

Daisuke Kobayashi et al. Molecules. .

Abstract

The convergent synthesis of the Lewis A (Le(a)) tandem repeat is described. The Le(a) tandem repeat is a carbohydrate ligand for a mannose binding protein that shows potent inhibitory activity against carcinoma growth. The Le(a) unit, {β-d-Gal-(1→3)-[α-l-Fuc-(1→4)]-β-d-GlcNAc}, was synthesized by stereoselective nitrile-assisted β-galactosylation with the phenyl 3-O-allyl-2,4,6-tri-O-benzyl-1-thio-β-galactoside, and ether-assisted α-fucosylation with fucosyl (N-phenyl)trifluoroacetimidate. This common Le(a) unit was easily converted to an acceptor and donor in high yields, and the stereoselective assembly of the hexasaccharide and dodecasaccharide as the Le(a) tandem repeat framework was achieved by 2-trichloroacetamido-assisted β-glycosylation and the (N-phenyl)trifluoroacetimidate method.

Keywords: Lewis A tandem repeat; convergent synthesis; sugar-binding protein.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Structure of the Lea tandem repeat.
Scheme 1
Scheme 1
Retrosynthetic scheme.
Scheme 2
Scheme 2
Synthesis of the Lea trisaccharide common intermediate.
Scheme 3
Scheme 3
Synthesis of Lea tetramer.
Scheme 4
Scheme 4
Introduction of a linker to the dodecasaccharide.
See this image and copyright information in PMC

References

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