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Pure Appl. Chem., 2013, Vol. 85, No. 9, pp. 1789-1801

Published online 2013-01-26

Stereocontrolled 1-S-glycosylation and comparative binding studies of photoprobe-thiosaccharide conjugates with their O-linked analogs

Lingquan Deng1, Xin Wang2, Suji Uppalapati2, Oscar Norberg1, Hai Dong1,3, Adrien Joliton1, Mingdi Yan1,2* and Olof Ramström1*

1 Department of Chemistry, Royal Institute of Technology (KTH), Teknikringen 30, S-10044, Stockholm, Sweden
2 Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., Lowell, MA 01854, USA
3 School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Rd. 1037, Wuhan, China

Abstract: The use of thioglycosides and other glycan derivatives with anomeric sulfur linkages is gaining increasing interest, both in synthesis and in various biological contexts. Herein, we demonstrate the occurrence and circumvention of anomerization during 1-S-glycosylation reactions, and present highly efficient and stereocontrolled syntheses of a series of photoprobe-thiosaccharide conjugates. Mutarotation of glycosyl thiols proved to be the origin of the anomeric mixtures formed, and kinetic effects could be used to circumvent anomerization. The synthesized carbohydrate conjugates were then evaluated by both solution- and solid-phase-based techniques. Both binding results showed that the S-linked glycosides interact with their cognate lectins comparably to the corresponding O-analogs in the present cases, thus demonstrating the reliability of the solid-support platform built upon our photo-initiated carbohydrate immobilization method for probing protein bindings, and showing the potential of combining these two means for studying carbohydrate–protein interactions.