title: Copper-mediated oxidative direct C-C (hetero)aromatic cross-coupling.
abstract: Some new types of copper-mediated intermolecular oxidative direct C-C (hetero)aromatic cross-couplings are described. A combination of the simple CuCl(2) salt and molecular oxygen allows 1,3-azoles to couple with terminal alkynes directly to form the corresponding heteroarylacetylenes. This direct version of Sonogashira-type coupling can be applied to the reaction with polyfluoroarenes. A copper acetate complex enables direct biaryl coupling between 2-arylazines and 1,3-azoles even in the absence of any palladium catalysts. Moreover, the Cu-based protocol can be extended to the coupling with indoles and pyrroles, in which a catalytic variant is also possible by using an ideal co-oxidant, atmospheric oxygen. On the other hand, a copper-promoted annulative direct coupling of o-alkynylphenols and -anilines with 1,3-azoles can provide a unique dehydrogenative approach to C3-azolylbenzoheteroles from nonhalogenated and nonmetalated starting materials. In addition, a related N-azolylindole synthesis from similar substrates is also disclosed.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Osaka University, Suita, Osaka 565-0871, Japan. k_hirano@chem.eng.osaka-u.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Hirano
authors.forename: Masahiro
authors.initials: M
authors.lastname: Miura
mesh_terms: D003300:Copper / Q000737:chemistry*; D006841:Hydrocarbons, Aromatic / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D006841:Hydrocarbons, Aromatic; D009942:Organometallic Compounds; D003300:Copper