Selective electrochemical glycosylation by reactivity tuning1

Abstract

Electrochemical glycosylation of a selenoglycoside donor proceeds efficiently in an undivided cell in acetonitrile to yield beta-glycosides. Measurement of cyclic voltammograms for a selection of seleno-, thio-, and O-glycosides indicates the dependence of oxidation potential on the anomeric substituent allowing the possibility for the rapid construction of oligosaccharides by selective electrochemical activation utilising variable cell potentials in combination with reactivity tuning of the glycosyl donor. A variety of disaccharides are readily synthesised in high yield, but limitations of the use of selenoglycosides as glycosyl donors for selective glycosylation of thioglycoside acceptors are exposed. The first electrochemical trisaccharide synthesis is described.

Synthesis of Disaccharide Nucleosides by the O‐Glycosylation of Natural Nucleosides with Thioglycoside Donors

“…In addition, the reactions of 31 [34] and 33 [35] with 10 c afforded 32 and 34 in 46 % (a/b = 3:1) and 57 % (a/b = 2.5:1) yields, respectively (Scheme 4 b and 4 c). For comparison, the reaction of 10 a, which contains TBDMS at the 3'-OH group (see Table 1), with 33 resulted in a negligible yield of the desired product.…”

Chemical Synthesis of the Pentasaccharide Related to the Repeating Unit of theO-Antigen fromSalmonella entericaO4

“…In a separate experiment, known glucosyl derivative 9 [15] was chloroacetylated at the 6-O-position using chloroacetic anhydride [16] and pyridine in CH 2 Cl 2 at 0 • C to afford compound 10 in 91% yield. Next, the thioglycoside was hydrolyzed using NBS [17] in an acetone-H 2 O (10:1) mixture to give the corresponding hemiacetal 11 in 87% yield.…”

Concise and Versatile Synthesis of Sulfoquinovosyl Acyl Glycerol Derivatives for Biological Applications

“…The β-thioglycoside 14 was prepared by the S-glycosylation of 8 with p-toluenethiol followed by deacetylation using NaOMe in methanol. The OH group at the 6-position of 14 was protected with a trityl group, 21) which was then converted into 17.…”