N-Hetero cyclic carbene catalysis for facile access to Pentasubstituted 4-H Pyran derivatives

The synthesis of multi-substituted 4-H Pyrans derivatives has drawn considerable attention due to its wide application in agrochemicals, pharmaceuticals, and other functional molecules. Herein, we report an N-heterocyclic carbene (NHC)-catalyzed [3+3] annulation reactions between -ketone esters and enynals for quick access to penta-substituted 4-H Pyran derivatives via a regioselective activation of ynals. A series of 4-H Pyrans derivatives bearing various substituents were obtained in moderate to excellent yields. This method may find further applications in the synthesis of structurally diverse 4-H Pyrans derived functional molecules from readily available starting materials.