Nickel Or Palladium-catalyzed Activation And Transformation Of C-O,C-N And C-F Bonds

This thesis focuses on nickel-or palladium-catalyzed activation and transformation of C-O,C-N and C-F bonds.A series of pyrazole-based ligands and mono-and di-nuclear nickel complexes and heterometallic nickel/palladium complexes supported by the ligands were synthesized and characterized.The catalytic properties of the complexes in the activation and transformation of C-O,C-N and C-F bonds were evaluated.Nickel-catalyzed activation and transformation of C-O bond of β-carbonyl alkenyl pivalates and palladium-catalyzed C-N cleavage of benzylic ammonium triflates are also presented.Chapter 1 describes synthesis and characterization of pyrazolyl-bridged bisphosphine ligand precursor 1.2 and pyrazolyl-bridged phosphine/iminophosphane ligand precursor 1.3 as well as complexes derived from the ligands including mononuclear nickel complexes 1.4-1.5,binuclear nickel complexes 1.6-1.7,and heteronuclear nickel/palladium complexes 1.8-1.9.The complexes are paramagnetic and were characterized by elemental analysis.The structures of complexes 1.6a and 1.9a were further confirmed by single crystal X-ray diffraction techniques.Chapter 2 presents evaluation of the catalytic properties of the complexes described in chapter 1 in the cross coupling reaction of naphthyl methyl ethers or fluorobenzenes with aryl Grignard reagents and phenyl quaternary ammonium salts with arylzinc reagents.Reaction kinetics catalyzed by complexes 1.5c,1.7c and 1.9c were studied.Among the complexes,1.6b shows the highest catalytic activity and both 1.8a and 1.9b exhibit the lowest catalytic activity.The kinetics test results also showed that cooperativity between the metals might be present in the coupling reaction of naphthyl methyl ether with Grignard reagent.However,in the reaction of phenyl quaternary ammonium salt with zinc reagent,the two metal centers of the catalyst showed a mutual inhibition effect.Chapter 3 describes NiCl2(PCy3)2-catalyzed cross-coupling of(3-carbonyl alkenyl pivalates with arylzinc chlorides under mild reaction conditions.The reaction exhibits a wide scope of substrates.Acyclic and cyclic β-carbonyl alkenyl pivalates,electron-rich and electron-poor arylzinc chlorides,2-furylzinc chloride and 2-thienylzinc chloride are suitable for this transformation.A range of functional groups are tolerated.Chapter 4 is about palladium-catalyzed direct benzylation of azoles withbenzylic ammonium triflates.The method displays a wide scope of substrates.The azoles include 4-and 5-aryloxazoles,benzoxazoles,and 2-phenyl-1,3,4-oxadiazole.The benzylic ammonium salts include various substituented phenylmethyl-ammonium triflates,naphthylmethylammonium triflates,and 2-thienylmethyl-ammonium triflate.Functional groups such as F,CF3,COOEt,C(O)NMe2,OMe,OPh,pyridyl and thienyl groups can be tolerated.The coupling reaction of benzothiazole with benzyltrimethylammonium triflate was also carried out by using the same catalyst system.