Organic Letters
Letter
stability toward the hydrazine used for Lev deprotection.16
Quantitative capping was achieved by incubating the resin-
bound oligogalactan for 30 min at 40 °C with a solution of
benzoic anhydride and DMAP in DCE. After capping the
backbone, the side chain was introduced by iterative Lev
deprotection and glycosylation reactions. The arabinose
building block BB4 was selectively attached to the side chain
after Fmoc deprotection.
The glycosylation conditions established for the synthesis of
oligogalactans 1−7 were also applied for oligosaccharides 8−
14, except that thioglycoside BB4 was activated with N-
iodosuccinimide and catalytic amounts of TfOH in DCM. After
cleavage of the products from the solid support, global
deprotection, and purification, AG oligosaccharides 8−14
were obtained in yields between 9 and 17% based on the
calculated resin loading (Scheme 2).
In conclusion, we have established a general approach to
synthesize glycans found on AGPs. Automated glycan assembly
provided 14 type-II AG glycans that are valuable probes for
plant research. All products are equipped with an aminopentyl
linker at the reducing end and can be directly printed as
microarrays to determine the binding specificities of antibodies
that recognize plant cell wall glycans.
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ASSOCIATED CONTENT
* Supporting Information
■
S
The Supporting Information is available free of charge on the
(15) Using modified conditions from: Eller, S.; Collot, M.; Yin, J.;
Hahm, H. S.; Seeberger, P. H. Angew. Chem., Int. Ed. 2013, 52, 5858−
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Experimental procedures for solution- and automated
solid-phase reactions and characterization data for all
AUTHOR INFORMATION
Corresponding Author
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We gratefully acknowledge financial support from the Max
Planck Society, the German Research Foundation (DFG,
Emmy Noether program PF850/1-1 to F.P.), the Fonds der
chemischen Industrie (Liebig-fellowship to F.P.), and an ERC
Advanced Grant (AUTOHEPARIN to P.H.S.). We thank Dr.
K. Gilmore (Max-Planck-Institute of Colloids and Interfaces)
for critically editing this manuscript.
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