Design And Synthesis Of Novel Ligands And Their Application In Alkoxycarbonylation And Asymmetric Hydrogenation

In the process of the development of catalytic reaction,the design and development of new and highly efficient ligands has always played a significant role,and has been received extensive attention from both industry and academia.Among them,the rational application of novel ligands to metal-catalyzed reactions and the improvement of the reaction activity and selectivity on the basis of the original reactions is the ultimate goal in the design and synthesis of ligands,as well as the basic requirement for chemical and industrial development.In this thesis,the application of a series of carbazole ligands in the alkoxycarbonylation of unsaturated hydrocarbons catalyzed by Palladium is studied.At the same time,the effect of benzimidazole derivatives ofβ~3-amino acids as a nitrogen-containing ligand on the ruthenium-catalyzed asymmetric hydrogenation of ketones was also noted.The main research content is as follows:1.According to the synthetic method reported in the literature,a series of carbazole ligands(L1-L5)were constructed through C-N coupling and C-P coupling by using bromocarbazole as the starting material,and the catalytic efficiency of these ligands in palladium-catalyzed alkoxycarbonylation of unsaturated hydrocarbons using 1-octyne and methol as model substrates was investigated.The results showed that with using of the mixture of PdCl2/L3/methanesulfonic acid(1/4/6 mol%)as catalysts,acetonitrile as reaction solvent,under 60 bar carbon monoxide pressure,aliphatic or aromatic alkynes reacted with methanol smoothly at 60 ~oC for 16 h,and finally theα,β-unsaturated esters were successfully obtained with high selectivity(28 examples,45%-96%yields,95.0%-99.9%branched selectivity).2.According to the report of Sandoval and his colleagues,they found that chiralα-amino acid-derived benzimidazoles played a significant role on the activity and selectivity of Ru-catalyzed asymmetric hydrogenation of ketones.Thus,we explored the effect ofβ~3-amino acid-derived benzimidazoles on the asymmetric hydrogenation by increasimg the length of carbon chains between amino acid and imidazole.The results showed that catalyst C1-C4catalyzed asymmetric hydrogenation of ketones,products of S configuration were obtained smoothly with high yield and moderate enantioselectivity(Example:8,39%->99%yield and62.9%-98.7%ee).Here,catalyst C1-C4 were prepared by complexing ruthenium catalyst precursor,and double nitrogen ligand 2-(2-aminoethyl)benzimidazole(β-BIMA),and asymmetric phosphine ligands(like(S)-BINAP,(S,S)-DIOP,(S)-SegPhos or(S)-MeO–BIPHEP).At the same time,the prepared catalysts are also applied to the asymmetric hydrosilylation of ketones,but the enantioselectivity of the reaction needs to be improved.