Mechanochemical synthesis of phthalimides from terpenes via tandem Diels-Alder cycloaddition and iodine-mediated aromatization

Abstract

A solvent-minimized, two-step mechanochemical protocol has been developed for the synthesis of terpene-derived phthalimides via sequential Diels–Alder cycloaddition and iodine-mediated aromatization at room temperature. Efficient conversion of isoprene and maleimides by ball-milling yields adducts in up to 86% yield, followed by in situ aromatization using iodine and 1,1,3,3-tetramethylguanidine to furnish phthalimides in up to 82% yield. The process tolerates a range of functional groups and is sensitive to steric hindrance around the diene and dienophile. This method circumvents conventional thermal protocols, offering a scalable and operationally simple route to value-added aromatics from renewable feedstocks under ambient conditions.