The Synthesis And Reactivity Of Well-defined High-valent Cu(Ⅲ) Trifluoromethyl Complexes

Transition copper-catalyzed trifluoromethylation reactions have attracted widespread interest in recent years. As the ready and sustainable availability, non-toxic and easy-handling advantages of copper salts, copper-catalyzed trifluoromethylation reactions are potential for practical and large-scale preparation of fluorinated compounds. In the process of copper-mediated trifluoromethylation reactions, the real active Cu complexes in reaction solutions are elusive and often just simply delineated as “CuCF3” in most of the literature reports. So far, just a few literatures had reported the definite determination of the isolated Cu(I) trifluoromethyl complexes via their crystal structures. In recent years, there are increasing evidence proposing the involvement of high-valent Cu(Ⅲ) intermediates in many copper-mediated coupling reactions. However, up to now there have been only three examples reported concerning the preparation and characterization of Cu(Ⅲ) trifluoromethyl complexes. Furthermore, reactivity studies of well-defined Cu(Ⅲ) trifluoromethyl complexes remains even more scarce. In this thesis, there are two following aspects about synthesis of novel Cu(Ⅲ) trifluoromethyl complexes and their trifluoromethylation with arylboronic acids.Firstly, the synthesis of Cu(Ⅲ) complexes [(phen)Cu(I)(PPh3)2]+[Cu(Ⅲ)(CF3)4]- and(phen)Cu(Ⅲ)(CF3)3(phen denotes phenanthroline) in one pot at room temperature via oxidation of(phen)Cu(I)(PPh3)Br by AgF in the presence of TMSCF3 under N2 atmosphere.These Cu(Ⅲ) trifluoromethyl complexes have been isolated purely and fully characterized by using 1H, 19 F, 31 P NMR, elemental analyses and X-ray crystallography. Reactivity studies indicate that(phen)Cu(Ⅲ)(CF3)3 can react with aryl and heteroaryl boronic acids with diverse electronic properties to deliver trifluoromethylated arenes in good to quantitative yields in the mild reaction conditions.Secondly, with CuI, AgF and N or P-bidentate ligands as starting materials, TMSCF3 as trifluoromethyl source, a series of high-valent Cu(Ⅲ) trifluoromethyl complexes had been synthesized in one pot at room temperature. We have selected five bidentate ligands, such as1,10-Phenanthroline(phen), 2,2’-Dipyridyl(bpy), 1,2-Bis(diphenylphosphino)ethane(DPPE),Dimethylbisdiphenylphosphinoxanthene(Xant Phos), 2,2’-Bis(diphenylphosphino)-1,1’-binaphthyl(BINAP), and Cu(Ⅲ) trifluoromethyl complexes(phen)Cu(Ⅲ)(CF3)3(1),(bpy)Cu(Ⅲ)(CF3)3(2), [(DPPE)2Cu]+[Cu(CF3)4]-(3), [(Xant Phos)2Cu]+[Cu(CF3)4]-(4) and[(BINAP)2Cu]+[Cu(CF3)4]-(5) have been synthesized, isolated purelyand fully characterized by using 1H, 19 F, 31 P NMR, elemental analyses and X-ray crystallography. Reactivity studies indicate that complexes 1-5 can react with aryl and heteroaryl boronic acids with diverse electronic properties to deliver trifluoromethylated arenes in good to quantitative yields.