Iron-Catalyzed Synthesis of 9-Substituted Xanthenes

Significance

Reported is an efficient iron-catalyzed, microwave-promoted cascade benzylation-aromatic nucleophilic substitution of ortho-bromo benzyl derivatives with phenols to afford xanthenes. The benzylation reaction is carried out using FeCl₃ as catalyst under microwave irradiation followed by cyclization (C-O bond formation) with Cs₂CO₃. A variety of benzylating reagents (benzyl acetates, benzyl bromides, and benzyl carbonates) and phenols (bearing EDGs and EWGs) are suitable. The reaction affords both 9-aryl and 9-alkyl xanthene derivatives in good to high yields.