Efficient Access to Conjugated Dienones and Diene‐diones from Propargylic Alcohols and Enolizable Ketones: A Tandem Isomerization/Condensation Process Catalyzed by the Sixteen‐Electron Allyl‐Ruthenium(II) Complex [Ru(η3‐2‐C3H4Me)(CO)(dppf)] [SbF6]

A large variety of conjugated dienones R¹R²CCHCHC(R³)C(O)R⁴ and diene‐diones R¹R²CCHCHC{C(O)R³}C(O)R⁴ have been synthesized in high yields by reacting terminal propargylic alcohols HCCCR¹R²(OH) with enolizable ketones R³CH₂C(O)R⁴ and β‐dicarbonyl compounds R³C(O)CH₂C(O)R⁴, respectively. The process, which is catalyzed by the 16e^‐ (η³‐allyl)‐ruthenium(II ) complex [Ru(η³‐2‐C₃H₄Me)(CO)(dppf)] [SbF₆] associated with CF₃CO₂H, involves the initial isomerization of the propargylic alcohol into the corresponding α,β‐unsaturated aldehyde R¹R²CCHCHO (Meyer–Schuster rearrangement) and subsequent aldol‐type condensation.