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Pure Appl. Chem. Vol. 74, No. 1, pp. 69-75 (2002)

Pure and Applied Chemistry

Vol. 74, Issue 1

Novel cyclization and reductive coupling of bicyclic olefins with alkyl propiolates catalyzed by nickel complexes*

Dinesh Kumar Rayabarapu and Chien-Hong Cheng

Department of Chemistry, Tsing Hua University, Hsinchu 300, Taiwan

Abstract: In this article, new metal-mediated cyclization and reductive coupling reactions of bicyclic olefins with alkynes are described. Oxabicyclic alkenes undergo cyclization with alkyl propiolates at 80 C catalyzed by nickel complexes to give benzocoumarin derivatives in high yields. The reaction of bicyclic alkenes (oxa- and azacyclic alkenes) with alkyl propiolates at room temperature in the presence of the same nickel complex gave 1,2-dihydro-napthelene derivatives in good-to-excellent yields. This reductive coupling reaction proceeds under very mild conditions in complete regio- and stereoselective fashion. A mechanism to account for the coumarin formation and the reductive coupling is proposed.

*Lecture presented at the 11th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis (OMCOS-11), Taipei, Taiwan, 22-26 July 2001. Other presentations are presented in this issue, pp.1-186.
**Corresponding author.


 

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