title: Designing a Cu(II)-ArCu(II)-ArCu(III)-Cu(I) catalytic cycle: Cu(II)-catalyzed oxidative arene C-H bond azidation with air as an oxidant under ambient conditions.
abstract: On the basis of our recent discovery of high valent organocopper compounds, we have designed and achieved efficient copper(II)-catalyzed oxidative arene C-H bond azidation under very mild aerobic conditions by using NaN3 as an azide source. In the presence of a Cu(II) catalyst, a number of azacalix[1]arene[3]pyridines underwent direct arene C-H bond cupration through an electrophilic aromatic metalation pathway to form an arylcopper(II) intermediate. Oxidized by a free copper(II) ion, the arylcopper(II) intermediate was transformed into an arylcopper(III) species that subsequently cross-coupled with azide to furnish the formation of aryl azide products with the release of a copper(I) ion. Under ambient catalytic reaction conditions, the copper(I) species generated was oxidized by air into copper(II), which entered into the next catalytic cycle. Application of the method was demonstrated by the synthesis of functional azacalix[1]arene[3]pyridines by means of simple and practical functional group transformations of azide. The showcase of the Cu(II)-ArCu(II)-ArCu(III)-Cu(I) catalytic cycle would provide a new strategy for the design of copper(II)-catalyzed aerobic oxidative arene C-H bond activation and transformations.
authors.affiliation: Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yao
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Liang
authors.initials: L
authors.lastname: Zhao
authors.forename: De-Xian
authors.initials: DX
authors.lastname: Wang
authors.forename: Mei-Xiang
authors.initials: MX
authors.lastname: Wang
mesh_terms: D001386:Azides / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D015394:Molecular Structure; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*
chemical_list: D001386:Azides; D056831:Coordination Complexes; D016877:Oxidants; D011725:Pyridines; D003300:Copper