Synthesis of oligosaccharides of glucosamine by automated electrochemical assembly

The automated electrochemical assembly is one of our arrial points for development of electrochemical methods for oligosaccharide synthesis. The one-pot sequential process of activation of thioglycoside building block by electrochemical oxidation and coupling with thioglycoside building block can be carried out in automated manner, and muliple cycles of the process enables us to synthesis oligosaccharides with desired chain length. We have synthesized oligoglucosamines with β -1,6- and β -1,4-glycosidic linkages. Total synthesis of TMG-chitotriomycin and Myc-IV(C16: 0, S), which are biologically active oligoglucosamines derivatives, has also achieved. Ionic liquid tags were introduced to glucosamine building blocks to facilitate separation of products; however, they worked not only separation tag but also electrolyte and stereo-controlling group in electrochemical glycosylation. We also found that electrochemical glycosylation was also useful to convert linear oligosaccharides of glucosamines into the corresponding cyclic oligosaccharides. © 2021 Society of Synthetic Organic Chemistry. All rights reserved.