Synthesis And Catalytic Properties Of Chiral Phosphine-imidazoline PCN Pincer Palladium And Achiral NC_sp3O Pincer Palladium Complexes

In this dissertation, the synthesis, characterization and catalytic application of chiral PCN pincer palladium(II) complexes with phosphine-imidazolinylphenyl ligands and achiral NCsp3 O pincer palladium(II) complexes were studied. The main results are as follows:1. Synthesis, characterizaiton and catalytic properties of chiral PCN pincer palladium(II) complexes with phosphine-imidazolinylphenyl ligands(1) Synthesis and characterization of chiral PCN pincer palladium(II) complexes Chiral imidazolinylphenyl ligands 2a-e were synthesized in three steps from commercially available 3-methylbenzoic acid. Ligands 2a-e and KPPh2 were refluxed in THF for 12 h. After removing the solvent, the crude products were refluxed in toluene with Pd Cl2 and Et3 N for 12 h, and the chiral PCN pincer palladium(II) complexes with phosphine-imidazolinyl phenyl ligands were formed. The new compounds 2a-e and 3a-e were characterized by 1H NMR, 13 C NMR, HRMS and elemental analysis. The molecular structure of compounds 3b and 3c were unambiguously confirmed by single crystal X-ray diffraction analysis.(2) Application of chiral PCN pincer palladium(II) complexes in asymmetric hydrophosphination reaction of enonesThe catalytic properties of PCN pincer palladium(II) complexes in the asymmetric hydrophosphination of pyridine-functionalized enones with diphenylphosphine were investigated. The asymmetric hydrophosphination was studied under the condition of 5 mol % PCN pincer palladium complex 3d as catalyst, KOAc as base, and toluene as solvent, at 0 ℃ or at room temperature for 12 h, providing optically active phosphine derivatives in enantioselectivities of up to 67% ee.2. Synthesis, characterization and catalytic properties of achiral NCsp3 O pincer palladium(II) complexes(1) Synthesis and characterization NCsp3 O pincer palladium(II) complexesFirst, 2-ene acyl pyridine reacted with diphenyl phosphine via conjugate addition in the presense of chiral PCP pincer palladium compound. The catalytic products 7 were afforded after oxidized by hydrogen peroxide. Then in the presence of base, the compound 7 reacted with Pd Cl2 in CH2Cl2 at 50 ℃ for 12 h, the new achiral NCsp3 O pincer palladium compounds 8a-b were easily obtained via C-H bond activation. The new compound 8a was characterized by 1H NMR, 13 C NMR and elemental analysis. The molecular structure of 8a was further confirmed by single crystal X-ray diffraction analysis.(2) Application of achiral NCsp3 O pincer palladium(II) complexes in Suzuki coupling reactionThe catalytic properties of achiral NCsp3 O pincer palladium(II) complexes in Suzuki coupling reaction were studied. Almost quantitative cross-coupling products were gained in the reaction of aryl bromide with aryl benzylborate, using ethanol/water(v:v=1:1) as solvent, potassium carbonate as base, in air atmosphere under the condition of 70 ℃, 50 ℃ or even room temperature, and the final TON values were up to 192 000. B(OH)2Complex 8b K2CO3 Et OH:H2O=1:1Br R2R1R2R1...