title: Exploring bis(cyclometalated) ruthenium(II) complexes as active catalyst precursors: room-temperature alkene-alkyne coupling for 1,3-diene synthesis.
abstract: 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.
authors: Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108-6050 (USA).
authors: Jing
authors: J
authors: Zhang
authors: Angel
authors: A
authors: Ugrinov
authors: Yong
authors: Y
authors: Zhang
authors: Pinjing
authors: P
authors: Zhao
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D000475:Alkenes; D000480:Alkynes; D001391:Azo Compounds; D009942:Organometallic Compounds; D012428:Ruthenium
keywords: CH activation; homogeneous catalyst; ligand effects; ruthenium; synthetic methods