Condensation of reactive phenols with aromatic 1,2-diketones : A single step protocol for synthesis of benzo-fused γ-lactones

The condensation of certain reactive phenols with aromatic 1,2-diketones has been investigated under acid / Lewis acid catalysis. The reaction has provided in acceptable yields a single major product, identified as benzo-fused γ-lactone, 1,2-Aryl migration via the intermediacy of a cyclic zwitterionic intermediate is proposed to account for the formation of the γ-lactone products.