On the Valorisation of Chitin-Derived Furans by Ball Milling.

Aromatic compounds containing nitrogen atoms in their structure are currently obtained from non-renewable sources with the incorporation of nitrogen from ammonia, which is industrially produced by the highly energy demanding Haber process. To minimize the carbon footprint of nitrogen containing chemicals and drive the production of nitrogenated aromatic compounds in a Haber-independent manner, the use of furans derived from chitin has become an affordable and promising source for nitrogen fixation in compounds with high added-value. Herein, we address the challenge of using two chitin-derived furans, 3-acetamido-5-acetylfuran (3A5AF) and 3-acetamido-5-furfural aldehyde (3A5F), to favor the formation of exo Diels–Alder adducts and 4-acetylaminophthalimides using Mechanochemistry, as a more sustainable and cleaner synthesis compared to the classical methods in solution-phase. The Mechanochemistry activation is explored through the synthesis of novel 7-oxa-norbornene backbones and it showed an improvement in both yield and exo:endo selectivity when compared to solution-phase, with yields reaching up to 77% and selectivity >19:1. We also investigated the use of a less toxic and commercially available hydrazine in order to promote the synthesis of 4-acetylaminophthalimides from 3A5F in yields ranging 20–79%.