title: The mechanism of the phosphine-free palladium-catalyzed hydroarylation of alkynes.
abstract: The mechanism of the Pd-catalyzed hydroarylation and hydrovinylation reaction of alkynes has been studied by a combination of experimental and theoretical methods (B3LYP), with an emphasis on the phosphine-free version. The regioselectivity of the hydroarylation and hydrovinylation shows unexpected differences, which could be attributed mainly to the higher steric demand of the cyclohexenyl group as compared to the phenyl group. Hydroarylation of alpha,beta-acetylenic carbonyl substrates yields a very unusual anti-Michael selectivity, which is shown to result from reaction of the nonconjugated double bond, leaving the conjugation intact. In all cases were the regioselectivities reproduced by the calculations.
authors.affiliation: Department of Chemistry, Technical University of Denmark, Building 201 Kemitorvet, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Mårten
authors.initials: M
authors.lastname: Ahlquist
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Fabrizi
authors.forename: Sandro
authors.initials: S
authors.lastname: Cacchi
authors.forename: Per-Ola
authors.initials: PO
authors.lastname: Norrby
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry*; D001555:Benzene Derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D008024:Ligands; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry; D010720:Phosphines / Q000737:chemistry; D014753:Vinyl Compounds / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D000475:Alkenes; D000480:Alkynes; D001555:Benzene Derivatives; D008024:Ligands; D010720:Phosphines; D014753:Vinyl Compounds; D010165:Palladium