title: Synthesis of tetra-substituted 5-trifluoromethylpyrazoles via sequential halogenation/palladium-catalyzed C-C and C-N cross-coupling.
abstract: A mild and efficient protocol for the assembly of tetra-substituted 5-trifluoromethylpyrazoles is presented, involving halogenation at the 4-position of readily prepared tri-substituted 5-trifluoromethylpyrazoles to give 4-halo-1-phenyl-5-trifluoromethyl pyrazoles, and subsequent palladium-catalyzed Negishi or Buchwald-Hartwig cross-couplings to install carbon or nitrogen-based 4-substituents. Key to the success of these challenging cross-couplings is the use of XPhos and JosiPhos CyPF-tBu ligands, respectively.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Maria, 97105-900 Santa Maria, Brazil. helio.bonacorso@ufsm.br.
authors.forename: Carson
authors.initials: C
authors.lastname: Wiethan
authors.forename: Wilian C
authors.initials: WC
authors.lastname: Rosa
authors.forename: Helio G
authors.initials: HG
authors.lastname: Bonacorso
authors.forename: Mark
authors.initials: M
authors.lastname: Stradiotto
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D054879:Halogenation; D008024:Ligands; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*
chemical_list: D008024:Ligands; D011720:Pyrazoles; D010165:Palladium; D002244:Carbon; D009584:Nitrogen