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methylenecyclopropane; titanocene(II) and zirconocene(II) complexes; bis(eta(5)-indenyl)zirconium complexes; [2+2] and [3+2] cycloadditions
Abstract:
Methylenecyclopropane (1a) reacts with bis(trimethylphosphane)titanocene (8) and (eta(2)-1- butene)(trimethylphosphane)zirconocene (12a) via olefin complexes; e.g. 9, in a [2+2] cycloaddition to afford the metallacyclopentane derivates 10, 13 and 14. In contrast, a [3+2] cycloaddition reaction is observed with bis(eta(5)- Indenyl)(eta(2)-1-butene)(trimethylphosphane)zirconium (12b) to furnish the 1-zircona-4-methylenecyclohexane 15. Similarly, reactions of the complexes 8 and 12a with benzylidenecyclopropane (1c) give the olefin complexes 9c and 20, while a direct reaction between the indenyl complex 12b with le occurs to furnish the 1-zircona-2- benzylidenecyclobutane complex 21b which was characterised by X-ray crystallography. (C) 2002 Elsevier Science B.V. All rights reserved.
