Amino and amido polysaccharides have been extensively investigated due to their important biological activities and intriguing biomedical applications. Chemical modification of polysaccharides is an useful strategy to acquire semi-synthetic amino polysaccharide, which typically involves a three-step reaction: introducing a leaving group, azide displacement, and azide reduction. The final azide reduction to amine or amide is the key step and current methods are limited by chemoselectivity and solubility issues. We successfully demonstrate a novel approach to selectively reduce azide to amine by using 1,4-dithiothreitol (DTT) on different polysaccharides (pullulan and curdlan), different organic solvents (DMF, DMAc, and DMSO), and in presence of functional groups such as ester. We also discover a new approach to reduce azides to acetamides on curdlan and pullulan by using thioacetic acid in both organic solvent and water, which is new to polysaccharide chemistry and cannot be obtained by any current method. Chemoselectivity and reaction mechanism were explored as well. The novel azide reduction by DTT and thioacetic acid provides an access to amino and amido polysaccharides that will be of great interest for exploring future applications and understanding structure property relationship of amino and amido polysaccharides.

Azide reduction by DTT and thioacetic acid: A novel approach to amino and amido polysaccharide

2019 Spring National Meeting

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