Atom-Transfer Radical Cyclization with [Cu/bipy]@Si

Significance

A CuCl/bipyridine complex was ­immobilized in a polysiloxane gel which was prepared by treatment of polymethylhydrosiloxane with 4,4′-bis[(2-propenyl)oxy]-2,2′-bipyridine and 1,5-hexadiene (crosslinker) in the presence of Karstedt’s catalyst. The immobilized complex [Cu/bipy]@Si catalyzed the atom-transfer cyclization of N-vinyl- and N-allyl-α-halogenated acet­amides to give the corresponding cyclized products in 58 to >99% yield (eq. 2, 10 examples).