Diphenylphosphinic Acid‐Catalyzed and Tf ₂ O‐Promoted Efficient Synthesis of <i>γ</i> ‐Pyrones from <i>β</i> ‐Keto Ester Compounds

A diphenylphosphinic acid‐catalyzed and Tf 2 O‐promoted intermolecular condensation of β ‐keto ester compounds is developed. The catalytic amount of diphenylphosphinic acid can significantly enhance the reaction efficiency, enabling the isolation of a variety of γ ‐pyrone products in good to high yields. Several control experiments provided key insights into the mechanism, revealing the dual role of diphenylphosphinic acid: it acts not only as a Brønsted acid catalyst to accelerate the reaction but also as a Lewis base to capture the alkyl group. Furthermore, this reaction can be successfully scaled up without loss of efficiency, demonstrating its potential for large‐scale industrial applications.