Application of levulinic acid ester as a protective group in the synthesis of oligosaccharides

Abstract

Abstract The fast, selective and mild removal of levulinoyl groups with hydrazine from galactose, which also carries hydroxyl functions protected with acetyl groups, enabled us, under Koenigs‐Knorr conditions, to synthesize tri‐ and tetrasaccharides containing β‐linked galactose and glucose units. Selective acylation of the primary alcoholic group of the partially protected galactose derivative 13b with levulinic acid was achieved in good yield. The preparation of tetrasaccharide 18b , having a free hydroxyl function, was effected by condensing dimer 16b with the bromo derivative 17 , followed by the removal of the levulioyl group with hydrazine.