title: Copper(II) complexes incorporating poly/perfluorinated alkoxyaluminate-type weakly coordinating anions: syntheses, characterization and catalytic application in stereoselective olefin aziridination.
abstract: The synthesis and characterization of a series of cationic copper(II) complexes of the type [Cu(NCR)(6)][Al(OC(CF(3))(2)R')(4)](2) (R = CH(3), Ph; R' = CF(3), Ph, PhCH(3)), incorporating poly/perfluoronated alkoxyaluminates as weakly coordinating anions (WCAs) is presented. Aziridination of various olefins, such as the unreactive olefins e.g. ethylhex-2-enoate and 1-decene, with N-tosyliminophenyliodinane catalyzed by [Cu(NCR)(6)][Al(OC(CF(3))(2)R')(4)](2) affords very good yields (up to 96%) and high TOFs (up to 5000 h(-1)) under mild conditions. Using disubstituted olefins as substrates, high stereoselectivities are obtained at room temperature. The to date highest cis : trans ratio (98 : 2) of the obtained aziridines is achieved for cis-stilbene in good yield (85%) as well as promising TOF (> 2000 h(-1)). The investigation of the solvent effect on yield and selectivity reveals that for certain oleophilic substrates (1-decene), less polar solvents, such as dichloromethane are a better choice than acetonitrile, which is commonly considered as the best solvent for olefin aziridination. Accordingly, a mechanism involving a paramagnetic copper nitrene intermediate with both concerted and stepwise pathways is proposed.
authors.affiliation: Molecular Catalysis, Catalysis Research Center, Technische Universität München, Ernst-Otto-Fischer-Str. 1, D-85747, Garching, Germany.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Jiayue
authors.initials: J
authors.lastname: He
authors.forename: Vineeta
authors.initials: V
authors.lastname: Khankhoje
authors.forename: Eberhardt
authors.initials: E
authors.lastname: Herdtweck
authors.forename: Klaus
authors.initials: K
authors.lastname: Köhler
authors.forename: Oksana
authors.initials: O
authors.lastname: Storcheva
authors.forename: Mirza
authors.initials: M
authors.lastname: Cokoja
authors.forename: Fritz E
authors.initials: FE
authors.lastname: Kühn
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000535:Aluminum / Q000737:chemistry; D000838:Anions / Q000737:chemistry; D001388:Aziridines / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005461:Fluorine / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D000475:Alkenes; D000838:Anions; D001388:Aziridines; D056831:Coordination Complexes; D005461:Fluorine; D003300:Copper; D000535:Aluminum