Cu(OTf) 2 -Phosphoric Acid-Catalyzed Tandem Oxa-Nazarov Cyclization and Dibromination of Conjugated 1,2-Diketones.

A facile tandem oxa-Nazarov cyclization and dibromination has been developed. The combination of Cu(OTf) 2 and diphenyl phosphate (DPP-H) was found to synergistically promote the coupling of conjugated 1,2-diketones and N- bromosuccinimide to form 2,4-dibromo-3(2 H) -furanones in good yields.