Electrochemical synthesis of 3-halogenated spiro [4,5]trienones based on dearomative spirocyclization strategy

A novel and green route have been developed for the electrochemical synthesis of 3-halogenated spiro[4.5]trienones based on dearomative spirocyclization of alkynes with NaX (Br, I) as the halogen source. This transformation was performed in an undivided cell under mild conditions. A wide range of substituted 3-halogenated spiro[4.5]trienones products was prepared in moderate-to-good yields, showing a broad scope and functional group tolerance. In addition, this approach was further extended to access fused tricyclic 6,7-dihydro-3H-pyrrolo[2,1-j]quinoline-3,9(5H)-diones.