Herein, we report the synthesis of sixmembered P,O-heterocycles from dialkynylphosphine oxides. By using gold(I) complexes, the chemoselectivity of the reaction was switched from literature-reported double hydration to a hydration/ intramolecular cyclization cascade. Control experiments indicated that the first alkyne hydration product is an intermediate of the reaction. In addition, a density functional theory (DFT) calculation allowed to rationalize the observed chemoselectivity.

By the design of suitable starting materials, a silver(I)‐catalyzed epoxide ring‐opening/1,2‐acyl migration/cyclization cascade has been developed, which allowed us to systematically prepare unsymmetrical 3‐formylfurans. Various 3‐formylfurans were prepared in good to excellent yields. In addition, the distinct fluorescence properties of 3‐formylfurans in solution and the solid state are disclosed.magnified image