Synthesis 2006(18): 3003-3008  
DOI: 10.1055/s-2006-942538
PAPER
© Georg Thieme Verlag Stuttgart · New York

Palladium-Catalyzed Cyclopentenone Formation by Carbonylative Cycloaddition of Allylic Tosylates and Alkynes

Naofumi Tsukada*, Shuichi Sugawara, Tomohiro Okuzawa, Yoshio Inoue
Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
Fax: +81(22)7955876; e-Mail: tsukada@aporg.che.tohoku.ac.jp;
Further Information

Publication History

Received 18 April 2006
Publication Date:
02 August 2006 (online)

Abstract

Carbonylative cycloaddition of allyl tosylates and alkynes proceeded in the presence of palladium catalysts to afford a range of cyclopentenones. In the presence of methanol, five-component coupling reactions gave methyl cyclopentenyl acetates, whereas­ in the absence of methanol, (cyclopentenoylmethylidene)furanones were formed from six components. Allyl tosylate was found to be essential for these reactions, as allyl acetate and allyl bromide proved to be ineffective.

9

The 2:1 ratio of palladium and PPh3 was also applied to the reactions in entries 5 and 6 because the yield of 7a was higher when using palladium and PPh3 in 2:1 ratio than in 1:1 ratio, although the 2:1 ratio is unusual.