Synthesis of regioselectively brominated cellulose esters and 6-cyano-6-deoxycellulose esters

The control of regiochemistry in the synthesis of polysaccharide derivatives is one of the most significant scientific challenges in the field. Its importance is only further highlighted by the individual successes in synthesis of regioselectively substituted derivatives, in particular cellulose esters and ethers, over the last 20 years. The availability of these samples and studies of their properties versus randomly substituted analogs has shown clearly that properties like solubility, aggregation phenomena, and optical properties depend heavily on the regiochemistry of substitution. We report here on the one-pot synthesis of novel 6-bromo-6-deoxy-2,3-O-acylcellulose derivatives, which as more organic soluble derivatives of 6-bromo-6-deoxycellulose should allow broader exploitation of the highly regioselective cellulose 6-bromination chemistry. We illustrate the potential of these new derivatives by conversion to 6-cyano-6-deoxycellulose esters.