Boosting 3-acetamido-5-acetylfuran production from N-acetyl-D-glucosamine in γ-valerolactone by a dissolution-dehydration effect

Abstract

Chitin biorefinery offers a unique opportunity to sustainably produce highly-valued organonitrogen compounds such as the versatile pharmaceutical precursor 3-acetamido-5-acetylfuran (3A5AF), bypassing the Haber process and mitigating the consumption of fossil feedstocks. However, the reported protocols engaged large quantities of toxic organic solvents and required harsh conditions. In this work, a highly efficient catalytic system has been developed in the nontoxic, biobased γ-valerolactone (GVL) solvent under relatively mild conditions. 3A5AF was selectively obtained with an unprecedent yield of 75.3% at 140 °C for 2 h by adding NH4SCN and HCl. The high yielding was exclusively promoted by a dissolution-dehydration effect. Based on the UPLC-TOF-MS and NMR analyses, the presence of NH4SCN has induced a very rapid NAG conversion possibly by coordinating with the acetamido group and the hydroxyl groups, and the 3A5AF product was obtained in a subsequent dehydration pathway from NAG with the Chromogen I and Chromogen III as the intermediates.