Effects of CoCl2 on the regioselective tosylation of oligosaccharides

• Published in: Journal of molecular structure 2021-10, Vol.1241, p.130609, Article 130609
• Main Authors: El-Abid, Jamal, Moreau, Vincent, Kovensky, José, Chagnault, Vincent
• Format: Article
• Language: English
• Subjects: Biochemistry, Molecular Biology; Cobalt catalyzed tosylation; Glycochemistry; Life Sciences; Regioselective reaction; Tosylation of oligosaccharides
• ISSN: 0022-2860; 1872-8014; 0022-2860
• DOI: 10.1016/j.molstruc.2021.130609

The tosyl functional group is commonly used in carbohydrate chemistry as a nucleofuge. Tosylation of the primary hydroxyls of carbohydrates are generally performed after orthogonal protection/deprotection reactions. However, it can be done regioselectively from unprotected sugars. Several examples have been described in the literature starting from free monosaccharides. Yields are generally good but may vary according to the nature of the sugar. Starting from free oligosaccharides, the regioselectivity and the yields generally drop significantly. The use of catalysts, such as DMAP or NEt3, improves the conversion but to the detriment of the regioselectivity. In our current work, we developed a tosylation reaction of the primary positions of several oligosaccharides with improved regioselectivity, using cobalt II chloride in catalytic amounts. Adaptability of this methodology has been tested on cellobiose, maltose, lactose, sucrose and maltotriose. •Development of a methodology for the regioselective synthesis of tosylated oligosaccharides•Highlighting of the effect of cobalt (II) chloride on the regioselectivity•Tests of the versatility of the method on different disaccharides and a trisaccharide•Characterization of new compounds using NMR, IR and HRMS [Display omitted]