Efficient and reusable PdCl2(MeCN)2/CuCl 2/PEG-400 system for cyclization of alkenyl β-keto esters and amides

Abstract

PEG-400 [poly(ethylene glycol-400)] was found as an effective medium for the PdCl2(MeCN)2-catalyzed hydroalkylation cyclization of alkenyl β-keto esters and amides. In PEG-400, no additives such as Me 3SiCl and Ln(OTf)3 were required for the complete conversion of alkenyl β-keto esters. The results also snowed that CuCl 2 could promote the reaction. In the presence of PdCl 2(MeCN)2, CuCl2, and PEG-400, various alkenyl β-keto esters and amides underwent a selective cyclization reaction to give good to excellent yields of the desired six-membered-ring carbocycles. Furthermore, the PdCl2(MeCN)2/CuCl2/PEG-400 system could be recycled and reused five times without any loss of catalytic activity. © 2005 American Chemical Society.