Terephthalic acid modified chitosan: A High-Performance Platform for Synthesis of Tetraketone Derivatives

Tetraketones are known as important and valuable building blocks in organic chemistry and pharmaceuticals due to the presence of several active carbonyl groups in their structure. Applications of these compounds include drug design, production of bioactive substances, and synthesis of metal ligands. In recent years, the use of bio-based heterogeneous catalysts has received attention as green and efficient alternatives. Chitosan, as a natural and biodegradable polymer rich in amine and hydroxyl groups, has a wide range of chemical modification capabilities and can be used as a suitable substrate for the design of efficient catalysts. In this study, chitosan modified with Terephthalic acid (CS–TPA) was prepared as a heterogeneous biobased catalyst and used in multicomponent reaction of 1,3-diketones with aromatic aldehydes to prepare tetraketone derivatives. The reactions were carried out with ethanol solvent and reflux conditions, with small amounts of catalyst and in high yield, and the products were obtained with suitable purity. The structure of the synthesized products and catalyst were confirmed using FT-IR and NMR and FESEM spectral analyses. Also, the possibility of recycling the catalyst and reusing it was investigated, which indicated its appropriate efficiency and stability. The results showed that CS–TPA can be considered as an efficient and environmentally friendly catalyst in the synthesis of tetraketones.