Staudinger reduction chemistry of cellulose: synthesis of selectively O-acylated 6-amino-6-deoxy-cellulose.

Aminated polysaccharides have been extensively investigated for a wide range of biomedical applications. To achieve targeted properties such as solubility and miscibility, it can be beneficial to modify the polysaccharide hydroxyl groups selectively while leaving the amino groups unmodified. This tends to be difficult because of the higher reactivity of primary amines than hydroxyl groups toward electrophilic reagents. We describe herein a new method that can produce O-acylated, aminated polysaccharides with extremely high selectivity. In this procedure, 6-azido-6-deoxy-cellulose esters are synthesized from 6-bromo-6-deoxy-cellulose esters. The azide groups are then selectively and mildly reduced using the Staudinger reaction to produce 6-amino-6-deoxy-2,3-di-O-acyl-cellulose derivatives. This demonstrates the effectiveness of the Staudinger reduction on a polysaccharide substrate in the presence of easily reducible ester groups.