Chemo-enzymatic approach to access diastereopure -substituted GlcNAc derivatives

The formation of diastereopure -substituted GlcNAc derivatives in a simple and straightforward way is a challenging task. Herein, we report the chemical synthesis of diastereomeric /-substituted GlcNAc derivatives under non-anhydrous atmosphere using unprotected GlcNAc, followed by a selective enzymatic hydrolysis step using a bacterial N-acetyl-hexosaminidase to provide only -substituted GlcNAc. This enzyme proved to selectively hydrolyze the -anomeric GlcNAc derivatives, while the -anomeric GlcNAc derivatives remained unreacted. The released GlcNAc (and therefore the / ratios) could be quantified using a coupled enzymatic assay consisting of GlcNAc 2-epimerase and N-acetyl- mannosamine dehydrogenase in a simple and accurate way.