Die Ruthenium-katalysierte Hydrovinylierung interner Alkine mit Acrylsäurederivaten - ein atomökonomischer Zugang zu hochsubstituierten 1,3-Dienen

Bifunctional Ligand Enables Efficient Gold-Catalyzed Hydroalkenylation of Propargylic Alcohol

Using the previously designed biphenyl-2-ylphosphine ligand, featuring a remote tertiary amino group, the first gold-catalyzed intermolecular hydroalkenylation of alkynes has been developed. Synthetically valuable conjugated dienyl alcohols are formed in moderate to good yields. A range of alkenyltrifluoroborates are allowed as the alkenyl donor, and no erosion of alkene geometry and/or the propargylic configuration are detected. DFT calculations confirm the critical role of the remote basic group in the ligand as a general-base catalyst for promoting this novel gold catalysis with good efficiency.

Exploring bis(cyclometalated) ruthenium(II) complexes as active catalyst precursors: room-temperature alkene-alkyne coupling for 1,3-diene synthesis

Described is the development of a new class of bis(cyclometalated) ruthenium(II) catalyst precursors for C-C coupling reactions between alkene and alkyne substrates. The complex [(cod)Ru(3-methallyl)2] reacts with benzophenone imine or benzophenone in a 1:2 ratio to form bis(cyclometalated) ruthenium(II) complexes (1). The imine-ligated complex 1 a promoted room-temperature coupling between acrylic esters and amides with internal alkynes to form 1,3-diene products. A proposed catalytic cycle involves C-C bond formation by oxidative cyclization, β-hydride elimination, and C-H bond reductive elimination. This Ru(II)/Ru(IV) pathway is consistent with the observed catalytic reactivity of 1 a for mild tail-to-tail methyl acrylate dimerization and for cyclobutene formation by [2+2] norbornene/alkyne cycloaddition.