Preparation Of Supported Catalysts And Their Catalytic Properties

Proline and its derivatives in asymmetric catalysis have achieved remarkable results and extensive development.However,the problems such as poor solubility,a large amount of catalyst,limited substrate range,separation and recovery difficulties and other issues have always existed.In order to improve these defects,the immobilized technology of proline and its derivatives can be a better solution to reduce the cost of catalyst preparation,improving the catalytic mode or the multi-functional catalytic method,and thereby increasing the catalytic efficiency,while increasing the recycling rates more in line with the concept of green chemistry.In this dissertation,combining with the present field of asymmetric catalysis and the new ideas and methods of green chemistry,the research was unfolded mainly on the design,synthesis and application of supported catalyst.Using the ordered and mesoporous carbon cage-like nano-materials or ionic liquids as the carrier,chiral catalysts were designed,synthesized,and used in the different asymmetric organic reaction.The experimental results are satisfactory.Main research contents can be summarized as follows:(1)With(2S,4R)-4-hydroxy proline as the material,a series of proline or prolinol derivatives were prepared,which were modified successfully to the surface of nanocage mesoporous carbon material(CKT-3)in the form of covalent bonds though a radical reaction,thus a new kind of recyclable organic catalyst(A1,A2)was prepared.Their structures were characterized,and these catalysts were then used to catalytic the direct asymmetric aldol reactions between cyclohexanone and substituted benzaldehyde.The results suggest that this type of catalysts have excellent activity(yield up to 72%)and enantioselectivity(anti/syn up to 73/27,ee up to 76%)for most aromatic aldehyde substrate,and their later usage need to research deeply.(2)A kind of new chiral organocatalyst Bi was designed and synthesized by using ionic liquid supported L-proline unit,and further used to catalytic the asymmetric Michael addition reactions between cyclohexanone and nitrostyrene compounds.The optimum conditions for the reaction were as follows:the nitrostyrene(1.0 mmol),cyclohexanone(2.0 mmol),catalyst B1(0.1 mmol),triethylamine(0.15 mmol)and methanol(2 mL)mixed.The reaction was stirred at room temperature.The range of reaction substrates was also extended.The target product can be synthesized in good yields(78%?98%)and enantioselectivity(dr up to 97%,ee up to 98%).It is noteworthy that this chiral catalyst can also be recycled 5 times without reducing the yield and enantioselectivity.(3)Twelve kinds of cinnamic acid derivatives were synthesized by using the Knoevenagel-Doebner synthesis method under microwave irradiation using L-proline/pyridine catalyzed system.(2R)-N-Boc-4-oxopyrrolidine-2-carboxylic acid methyl ester was synthesized by Swern oxidation method and used as a chiral ketone catalyst.Oxone was used as oxidant.We explored the simple synthetic route of natural product-tanshinol by using the asymmetric catalytic epoxidation reaction of cinnamon acid as template.However,it is a pity that the yield and enantioselectivity were inferior to the Sharpless asymmetric epoxidation catalyzed by metal catalysts,and the preparation of chiral drug catalyzed by small organocatalysts without metal left has also not been realized.The preparation of chiral ketone catalysts still need to be further studied.(4)By using the method of self-made mesoporous carbon materials(CKT-3)supported metal palladium to prepare catalyst Pd-CKT,which was successfully used in the Heck coupling reaction between halobenzene compounds and propylene,and the target compound 1-phenyl propylene derivatives were thus synthesized by one-step reaction.The reaction conditions were optimized(substrate 10 mmol,catalyst 0.3 mmol%,110?),and based on this,the extended experiments for the adaptability of the substrates were performed,and the good results(yield:65%-87%)were achieved.By comparison,the catalyst Pd-CKT has better application prospect than the conventional palladium acetate catalysis system,both in terms of catalyst dosage,substrate adaptation range,mixture post-treatment and reaction conditions.Therefore,this catalyst has good application prospect.