A novel synthesis of acridones via iron(II)-catalyzed intramolecular acylation of N-phenylanthranilic acids

Abstract

A practical and efficient strategy for the synthesis of N–H acridones via intramolecular Friedel–Crafts-type cyclization of N-phenylanthranilic acids is reported. The reaction proceeds under mild, ligand-free conditions using a cooperative catalytic system comprising Fe(OTf)₂ and dichloromethyl methyl ether (DCME). This methodology features a broad substrate scope, providing functionalized acridones with high regioselectivity, very good to excellent yields, and high atom economy. The synthetic utility of the transformation is further demonstrated by the gram-scale preparation of a bioactive acridone with established antiviral activity.