Mechanochemical synthesis of bis-benzoquinonylmethanes promoted by sulfonic acid-functionalized chitosan

A sustainable mechanochemical method for synthesizing functionalized bis-lawsones from 2-hydroxynaphthalene-1,4-dione and aldehydes under solvent-free conditions is described. Sulfonated chitosan acts as both a biodegradable grinding auxiliary and a solid acid promoter, enabling high yields, broad tolerance to aryl-substituted aldehydes, and recyclability over multiple cycles with minimal loss of activity. The protocol is readily scalable without compromising efficiency.