Catalytic atom-transfer radical cyclization by copper/bipyridine species encapsulated in polysiloxane gel

Chem Commun (Camb). 2010 Apr 7;46(13):2256-8. doi: 10.1039/b923213c. Epub 2010 Jan 21.

Abstract

Novel polysiloxane gel, in which CuCl/bipyridine species are immobilized, is prepared by treatment of polymethylhydrosiloxane with 4,4'-bis[(2-propenyl)oxy]-2,2'-bipyridine and 1,5-hexadine in the presence of Karstedt's catalyst followed by addition of CuCl. This polysiloxane gel acts as a reusable catalyst in the atom-transfer radical cyclization of alpha-halogenated acetamide derivatives in high turnover numbers without allowing leakage of the metal species.