The Synthesis Of NCN Pincer Iridium Complexes And Catalytic Properties Of PCN Pincer Pdlladium Complexes

This dissertation is mainly focused on the synthesis and characterization of aseries of chiral NCN pincer iridium(III) complexes with bis(imidazolinyl)phenylligands and the application of PCN pincer palladium(II) complexes in asymmetricconjugate phosphination are also explored. The main results are as follows：1. Synthesis and characterization of chiral NCN pincer iridium(III) complexeswith bis(imidazolinyl)phenyl ligandsA series of chiral bis(imidazolinyl)phenyl ligands1a-k were synthesized in atwo/three-step sequence from inexpensive benzene dicarbonyl dichloride or5-tertiarybutyl-m-phthalic acid and chiral amino alcohols. Then the reaction of1a-k and triplyhydrated iridium trichloride led to the formation of corresponding chiralbis(imidazolinyl)phenyl NCN pincer iridium(III) complexes [(Phebim)IrCl2(H2O)]2a-k via the direct Caryl-H bond activation strategy. The complex[(Phebim)Ir(OAc)2(H2O)]3was readily derived from2f by reaction with an access ofsilver acetate(Scheme1). All of the new complexes were characterized by1H NMR,13C NMR and elemental analysis (new ligands1f-k by HR-MS). The structures of thecomplexes2e and2i were further confirmed by single-crystal X-ray analysis. 2. The application of chiral PCN pincer palladium(II) complexes in asymmetricconjugate phosphination reaction.(1) Synthesis and characterization of PCN pincer palladium(II) and nickel(II)complexesAccording to the synthesis method of our laboratory reported, imidazolinylm-phenol compounds were prepared from commercially available m-hydroxybenzoicacid by four steps sequencing reaction. With the expected ligand precursors in hand,the unsymmetrical PCN pincer palladium(II) and nickel(II) complexes4a-e and5could be accessed via the “one-pot phosphorylation/metallization” approach (Scheme2). The new complex5was characterized by1H NMR,13C NMR，31P NMR andelemental analysis. The structures of the complex5was further confirmed bysingle-crystal X-ray analysis. (2) Application of chiral PCN pincer palladium(II) complexes in the asymmetricconjugate phosphination reaction.The enantioselectivities and catalytic activities of the five pincer Pd(II)complexes4a-e in asymmetric addition reaction of diarylphosphine and2-enoylpyridine/2-enoyl pyridine-N-oxides were investigated. Results indicate that complex4a displayed the efficient enantioselectivity, under the condition of5mol%catalystloading, toluene as solvent, KOAc as base and-10oC/0oC, the adducts could beenobtained with up to85%(83%) yield and95%(83%) ee (Scheme3).