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.