Carbonylation Of Epoxides/Methyl Acrylate

Homogeneous carbonylation reactions are a process in which organic compounds（such as unsaturated hydrocarbons,halogenated hydrocarbons or epoxides,etc.）,CO and nucleophiles（such as organic amines,alcohols or water,etc.）are used as raw materials to prepare high value-added carbonyl compounds under the catalysis of homogeneous transition metal catalysts.The reactions have the characteristics of cheap and easy availability of raw materials,high atomic utilization,and high dependence on homogeneous precious metal catalysts.Phosphine ligand-modified transition metal complexes are commonly used as catalysts for carbonyl reactions,and the electronic and steric effects of ligands significantly affect the activity,selectivity and stability of transition metal catalysts.In this thesis,the aminocarbonylation and methoxycarbonylation of epoxides catalyzed by ligands-modified cobalt catalysts as well as the methoxycarbonylation of methyl acrylate catalyzed by ligands-modified palladium catalysts were investigated.The obtained results are summarized as follows.（1）Cobalt-catalyzed aminocarbonylation of epoxides for preparation ofβ-hydroxyamidesβ-hydroxyamide compounds are widely used as important organic synthesis intermediates because they contain hydroxyl groups and amide groups,which can undergo various reactions such as oxidation,hydrolysis and hydrogenation.In this part,the aminocarbonylation of epoxides,CO and organic amines catalyzed by different ligands-modified Co₂（CO）₈to prepareβ-hydroxyamides in one step was investigated.The experiment results showed that the CO₂（CO）₈catalytic system modified by the bidental O-containing ligand of L2,which was prepared via the oxidation of the diphosphine of Xantphos（L1）,exhibited the best catalytic performance.Under the optimal reaction conditions(Co₂（CO）₈2.5 mol%,L2 2.5mol%,v _THF/v_dioxane=1/1,60℃,CO 3.0 MPa,6 h),the conversion of aniline was 83%,and the yield ofβ-hydroxybutyamide was 64%.Upon three-cycle reuses of the catalyst,the average yield of the target product maintained at 55%.The generality of the substrates is only limited to the aromatic amines.Compared with Xantphos,L2,as a bidental O-containing ligand with better thermodynamic stability,is more conducive to the stability of Co catalysts.（2）Cobalt-catalyzed methoxycarbonylation of epoxides for preparation ofβ-hydroxycarboxylic estersβ-hydroxycarboxylic esters are a class of structurally stable bifunctional compounds that are used as important intermediates in the synthesis of drugs,fragrances,agrochemicals and natural products.In this part,the methoxycarbonylation of epoxides,CO and alcohols catalyzed by N-containing ligands-modified Co₂（CO）₈to prepareβ-hydroxycarboxylic esters in one step was examined.The experiment results showed that the catalytic system of Co₂（CO）₈modified with N-containing ligand L9 showed good catalytic activity and selectivity in the carbonylation reaction of epoxides.Under optimal reaction conditions(Co₂（CO）₈5 mol%,L9 10 mol%,Al（OTf）₃2 mol%,v _THF/v _{Me OH}=1/1,60℃,CO 4.0MPa,8 h),propylene oxide can achieve efficient conversion to the target product methyl 3-hydroxybutyrate with a yield of 91%,and has good substrate universality.In addition,there was no significant deactivation of the catalyst after four-cycle reuses.（3）Palladium-catalyzed methoxycarbonylation of methyl acrylate for preparation of dimethyl succinateDimethyl succinate is an important chemical intermediate in the preparation of fragrances,pharmaceuticals,food additives and other fine chemicals.In this work,a series of phosphine ligands were applied to the methoxycarbonylation of methyl acrylate,CO and methanol catalyzed by Pd catalysts for the preparation of dimethyl succinate in one step,and the effects of different ligands on the reaction were investigated.It was found that the palladium-catalyzed system modified by two phosphine ligands LII-1 and LII-2 showed the best catalytic performance in the methoxycarbonylation of methyl acrylate.Under the optimal reaction conditions（[Pd]0.2 mol%,L13 0.6 mol%,L14 0.4 mol%,MeSO₃H 2 mol%,CO 3 MPa,140℃,6 h）,methyl acrylate was completely converted,and led to 89%yield of dimethyl succinate.Notably,the catalyst still has good catalytic activity after twenty-cycle reuses.