Transition-metal-promoted activation of carbon-carbon bonds. A new synthetic route to substituted ruthenocene derivatives via ring expansion reactions of 3-vinyl-1-cyclopropenes

Article abstract of DOI:10.1021/om00106a023

A new route to substituted ruthenocenes is described. The reaction of [Ru(η⁵-C₅H₅)(η⁴-C ₈H₁₂)X] (C₈H₁₂ = 1,5-cyclpoctadiene; X = Cl, Br), [Ru(η⁵-C₉H₇)(η⁴-C ₈H₁₂)Cl] (C₉H₇ = indenyl), and [(Ru(η⁵-C₅Me₅)Cl}₄] with substituted 3-vinyl-1-cyclopropenes (1) provides a high-yield route to a range of substituted ruthenocenes, [Ru(η⁵-C₅H₅)(η⁵-C ₅R₅)] {2, C₅R₅ = C₅H₂Ph₃-1,2,3; 3, C₅R₅ = C₅H₃Ph₂-1,2; 4, C₅R₅ = C₅H₂Ph₂-1,2-Me-4; 5, C₅R₅ = C₅HMePh₃-1,2,3}, [Ru(η⁵-C₅H₂Ph₃-1,2,3)] (6), and [Ru(η⁵-C₅Me₅)(η⁵-C ₅H₂Ph₃-1,2,3)] (7). No intermediates in these reactions could be detected by ¹H or ¹³C{¹H} NMR spectroscopy. The cis-α,-β-disubstituted vinylcyclopropene 1,2,3-triphenyl-3-(cis-β-methylvmyl)-1-cyclopropene (1e) reacts more rapidly than its trans isomer 1d, but both yield the same ruthenocene derivative 5. Treatment of [Ru-(η⁵-C₅H₅)(η⁴-C ₈H₁₂)Cl] with K[C₅H₂Ph₃-1,2,3] rapidly gives the expected 1,2,3-triphenylruthenocene derivative 2, while the reaction of [Ru(η⁵-C₅H₅)(η⁴-C ₈H₁₂)Cl] or [{Ru(η⁵-C₅Me₅)Cl}₄] with 1,2,3-triphenylcyclopentadiene proceeds more slowly to yield complexes 5 and 7, respectively. [Ru(η⁵-C₅H₅)(η⁴-C ₈H₁₂)Cl] reacts similarly with cyclopentadiene to give [Ru(C₅H₅)₂].