Effects of CoCl2 on the regioselective tosylation of oligosaccharides

Jamal El-Abid , Vincent Moreau (1, 2) , José Kovensky (2) , Vincent Chagnault (2)

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 LG2A - Laboratoire de Glycochimie, des Antimicrobiens et des Agro-ressources - UMR CNRS 7378

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. (C) 2021 Elsevier B.V. All rights reserved.

Domaines: Biochimie, Biologie Moléculaire

Jamal El-Abid, Vincent Moreau, José Kovensky, Vincent Chagnault. Effects of CoCl2 on the regioselective tosylation of oligosaccharides. Journal of Molecular Structure, 2021, 1241, pp.130609. ⟨10.1016/j.molstruc.2021.130609⟩. ⟨hal-03613796⟩