Carboxymethyl glucosides and carboxymethyl glucoside lactones: A detailed study of their preparation by oxidative degradation of disaccharides

A detailed study of the access to carboxylmethyl tri-O-acetyl-alpha-D-glucopyranoside 2-O-lactone from isomaltulose was performed. Side products can arise from incomplete oxidation of isomaltulose by hydrogen peroxide, acidic hydrolysis, or opening of the lactone during the acylation step. Based on these observations, the optimum conditions for the preparation of this interesting synthon, as well as of its benzylated and pivaloylated analogues, was determined. Also, the use of the hydrogenated analogue of isomaltulose, isomalto, as the starting material was studied. In this case, during the oxidation step, the catalysis by sodium tungstate proved to be indispensable to form carboxymethyl glucoside, unlike for isomaltulose. Although giving low yields, this reaction is very direct and was performed using cheap and simple procedures from a readily available substrate.