Synthesis 2005(12): 2061-2074  
DOI: 10.1055/s-2005-870029
SPECIALTOPIC
© Georg Thieme Verlag Stuttgart · New York

Zirconocene-Induced Cocyclisation/Elimination Reactions of 2-Heterosubstituted 1,6-Dienes and 1,6-Enynes

David R. Owen, Richard J. Whitby*
School of Chemistry, University of Southampton, Southampton, Hants, SO17 1BJ, UK
Fax: +44(23)80593781; e-Mail: rjw1@soton.ac.uk;
Further Information

Publication History

Received 15 February 2005
Publication Date:
14 July 2005 (online)

Abstract

Zirconocene-mediated cocyclisation of 2-heterosubstituted-1,6-dienes and -enynes gave zirconacycles bearing an endocyclic β-leaving group which eliminated under the reaction conditions to provide exocyclic alkylidene groups. The scope of this cyclisation/elimination has been investigated along with further elaboration of the monosubstituted zirconocene intermediates by insertion of alkenyl carbenoids.

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Molecular modeling studies were performed with Spartan 04 (Wavefunction inc.). Conformational searches were carried out using molecular mechanics (MMFF94 force field extended to include transition metals, and cyclopentadiene ligands). Final minimizations of likely global minima were carried out using the hybrid DFT/HF B3LYP method using the 6-31G* basis set, and core electron approximation for zirconium. [43]