2004

Cyclopentane derivativesQ 0030 Insertion of (E)-(1,2-Dihalovinyl)lithium and (2-Haloethynyl)lithium into Zircon-

acycles. — Unexpectedly, methylidenecyclopentenes (IV) are found as products of the title reaction. These compounds are somewhat unstable and decompose partly on chro-matography. Their formation is rationalized via insertion of (E)-(1,2-dihalovinyl)lithi-um into zirconacyclopentenes followed by elimination of halide to afford an alkyne which inserts intramolecularly into the resulting carbon-zirconocenium bond to give (IV). — (NORTON, D.; WHITBY*, R. J.; GRIFFEN, E.; Chem. Commun. (Cambridge) 2004, 10, 1214-1215; Sch. Chem., Univ. Southampton, Southampton SO17 1BJ, UK; Eng.) — M. Paetzel

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