Development of a Green Method for the Synthesis of Xanthene-1,8-dione Derivatives from Dimedone and Aldehydes

A green and efficient method was developed for the synthesis of 1,8-dioxo-octahydroxanthene derivatives using linear alkylbenzene sulfonic acid (LABSA) as an eco-friendly Brønsted acid catalyst under aqueous reflux conditions. This system combines micellar catalysis and acid activation to afford tricyclic products in high yields and with excellent purity. The transformation proceeds via a Knoevenagel–Michael sequence between dimedone and aromatic aldehydes, followed by intramolecular cyclization. The method exhibits broad substrate tolerance, affording yields between 80 and 92. The simplicity, scalability, and environmental compatibility of this process establish LABSA as a promising alternative to conventional acids for the green synthesis of pharmacologically relevant xanthene derivatives.