Copper-Catalyzed Cascade Radical Addition Cyclization Halogen Atom Transfer between Alkynes and Unsaturated α-Halogenocarbonyls

A Cu-catalyzed cascade radical addition/cyclization/halogen atom transfer between alkynes and ahalogeno-gamma, delta-unsaturated carbonyl compounds for the synthesis of various substituted cyclopentenes is described. Since up to four Csp(3)-Csp(2) bonds, two Csp(3)-Br bonds, and two carbocycles can be established in a single reaction, this 100% atom-efficient reaction exhibits the advantages of wide substrate scope, high functional group tolerance, and step economics, and it offers an entry of the atom transfer radical addition/cyclization (tandem ATRA-ATRC) process to the synthesis of substituted cyclopentenes.