2’-Cyanoethyl Thioglycosides: Effective Nucleophiles For Synthesis Of (Hetero) Aryl Thioglycosides Under The Catalysis Of Cu

Thioether motifs exist widely in medicines, pesticides and polymer materials. Thioglycosides are a type of sugar derivatives which contain C-S bond and are of great significance in glycochemistry. Thioglycosides function as a significant type of glycosylation donors which are widely applied in the synthesis of biologically potent oligosaccharides and glycoconjugates. In addition, many bioactive compounds are found to structurally feature thioglycoside units. Particularly in clinics thioglycosides are potentially therapeutic agents for treating diabetes. However, naturally occurring thioglycosides are too rare to satisfy the need for bioactive and structural study. Also, present methodologies for preparing thioglycosides suffer from many defects. So there is a need for alternative protocols which address the shortcomings of currently available methods.The paper firstly describe the advancement in the transition metal-catalyzed C-S bond formation. Then base on the role in the thioetherfication which Cu plays, we designed and synthesized a series of 2’-cyanoethyl thioglycosides as nucleophiles. These sulfur compounds reacted smoothly with organic iodides to afford aryl(hetero) thioglycosides under the catalysis of Cu. Structural characterization showed the absolute configuration at the anomeric position of these coupling products were retained without any epimerization. These novelty nucleophiles provide good conversion of a wide range of substrates in the mild conditions and they exhibit remarkably high functional group tolerance. In conclusion, our study address some problems in the current thioglycoside protocols and explore a simple, fast, low-cost method for the preparation of the thioglycoside, The result is expected to be applied to the synthesis of oligosaccharides.