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

J Org Chem. 2023 Jul 7;88(13):9584-9593. doi: 10.1021/acs.joc.3c01063. Epub 2023 Jun 1.

Abstract

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.

MeSH terms

  • Cycloaddition Reaction
  • Electrons
  • Ketones
  • Molecular Structure
  • Pyrazoles
  • Pyrazolones*
  • Stereoisomerism

Substances

  • Pyrazolones
  • Pyrazoles
  • Ketones