Efficient and reusable PdCl2(MeCN)2/CuCl2/PEG-400 system for cyclization of alkenyl beta-keto esters and amides.
PEG-400 [poly(ethylene glycol-400)] was found as an effective medium for the PdCl(2)(MeCN)(2)-catalyzed hydroalkylation cyclization of alkenyl beta-keto esters and amides. In PEG-400, no additives such as Me(3)SiCl and Ln(OTf)(3) were required for the complete conversion of alkenyl beta-keto esters. The results also showed that CuCl(2) could promote the reaction. In the presence of PdCl(2)(MeCN)(2), CuCl(2), and PEG-400, various alkenyl beta-keto esters and amides underwent a selective cyclization reaction to give good to excellent yields of the desired six-membered-ring carbocycles. Furthermore, the PdCl(2)(MeCN)(2)/CuCl(2)/PEG-400 system could be recycled and reused five times without any loss of catalytic activity.
Li
Jin-Heng
JH
Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China. jhli@hunnu.edu.cn
Zhu
Qi-Ming
QM
Liang
Yun
Y
Yang
Dan
D