Organocatalytic Asymmetric Inverse-Electron-Demand Diels–Alder Reaction between Alkylidene Pyrazolones and Allyl Ketones: Access to Tetrahydropyrano[2,3-c]pyrazoles

Herein we report a catalytic asymmetric inverse-electron-demand Diels–Alder reaction between alkylidene pyrazolones and allyl ketones. Allyl ketone gets activated by a bifunctional thiourea catalyst and acts as a dienolate in this reaction. The trisubstituted tetrahydropyrano[2,3-c]pyrazoles were obtained in moderate to good yields with high diastereo- and enantioselectivities. Few applications, including a decarbonylation reaction, have been demonstrated.