Copper-Catalyzed Radical-Triggered Annulation–Halocyanomethylation Reaction of Alkynyl-Bearing Bicyclo[1.1.0]butanes (BCBs) Leading to Spirocyclobutyl Quinolinones

The novel copper-catalyzed radical-triggered annulation-halocyanomethylation reaction, involving preprepared alkynyl-substituted bicyclo[1.1.0]butanes (BCBs) and haloacetonitrile, was reported for the first time, enabling the synthesis of various halocyanomethylated spirocyclobutyl quinolinones with moderate to high yields and perfect regioselectivity. This method exhibits broad substrate adaptability and exceptional functional group tolerance and is distinguished by its capacity to directly form up to three new chemical bonds while constructing a spirocyclic framework in a single step.