The Synthesis Of CCN Pincer Metal Complexes And Their Application In Asymmetric Catalysis

This thesis studies the synthesis and characterization of CCN pincer metal complexes and explores their applications in catalysis.The main results have been presented as follows:1.Synthesis and characterization of CCN pincer metal complexes（1）.Complexes 3-bromobenzoic acid,SOCl₂,（S）-（+）-2-phenylglycinol and p-toluidine can afford chiral 1-（imidazolinyl）-3-（bromine）benzene complex 1 in five steps.Complexes 1 and imidazole were refluxed in DMF for 18 h to afford complexes2,then complexes 2 and halohydrocarbon were refluxed in methylbenzene for 2-4 h to afford chiral CCN ligand 3（Scheme 1）.The new compounds 1、2 and 3 were characterized by ¹H NMR,¹³ C NMR and HRMS.（2）Synthesis and characterization of chiral CCN pincer Pd（Ⅱ）complexesLigands 3 and Pd（OAc）₂ were refluxed overnight in DMAc to afford chiral CCN pincer Pd（Ⅱ）complexes 4a-i（Scheme 2）.New compounds 4a-i were all characterized by ¹H NMR,¹³ C NMR,elemental analysis and HRMS.The molecular structures of4 a and 4c were further confirmed by the way of X-ray single crystal diffraction.（3）Synthesis and characterization of chiral CCN pincer Ni（Ⅱ）complexesLigands 3 and Ni Cl₂ were refluxed overnight in DMAc to afford chiral CCN pincer Ni（Ⅱ）complexes 5a-g（Scheme 3）.New compounds 5a-g were all characterized by ¹H NMR,¹³ C NMR,elemental analysis and HRMS.The molecular structures of 5e were further confirmed by the way of X-ray single crystal diffraction.2.The asymmetric aza-Morita–Baylis–Hillman reaction of imines and acrylonitrile catalyzed by chiral CCN pincer Pd（Ⅱ）compounds.The application of the CCN pincer Pd compounds 4a-i in the asymmetric aza-Morita–Baylis–Hillman reaction of imines and acrylonitrile was preliminarily explored.The reaction of（E）-N-benzylidene-4-methylbenzenesulfonamide with acrylonitrile was used as a template reaction.Preliminary investigation showed that,on the condition that 10 mol% 4f as catalyst,20 mol% DABCO as additive,5 mol%Ag OAc as additive,at-20℃ for 48 h,the isolated products were got with up to 66%yield and 66% ee;On the condition that 10 mol% 4c as catalyst,20 mol% DABCO as additive,5 mol% Ag OAc as additive,at-10℃ for 72 h,the isolated products were got with up to 97% yield and 8% ee（Scheme 4）.3.The asymmetric Friedel-crafts reaction of imines and indole catalyzed by chiral CCN pincer Pd（Ⅱ）compounds.The application of the CCN pincer Pd compounds 4a-i in the asymmetric Friedel-crafts reaction of imines and indole was preliminarily explored.The reaction of（E）-N-benzylidene-4-methylbenzenesulfonamide with indole was used as a template reaction.Preliminary investigation showed that,on the condition that 5mol% 4f as catalyst,10 mol% K2CO3 as base,10 mol% Ag OTf as additive,at 40℃ for 48 h,the isolated products were got with up to 99% yield and 33% ee（Scheme 5）.4.Applications of CCN-pincer Pd（Ⅱ）and Ni（Ⅱ）complexes in asymmetric hydrophosphination of nitroalkenes.The activities and enantioselectivities of 4a-i and 5a-g in asymmetric addition reaction of diarylphosphine to nitroalkenes were investigated.The reaction of diarylphosphine with nitroalkenes was used as a template reaction.Preliminary investigation showed that,on the condition that,10 mol% 4b,10 mol% Na OAc as base,and CHCl3 as solvent,at-20℃ for 12 h,the products were isolated after oxidation with up to 94% yield and 28% ee;10 mol% 5a,10 mol% Na OAc as base,and trichloropropane as solvent,at-20 oC for 12 h,the products were isolated after oxidation with up to 99% yield and 35% ee（Scheme 6）.