Biocatalytic Promiscuity:Enzyme Catalyzed Aldol, Henry,and Synthesized2H-1-benzopyran-2-one Derivatives

Development of green catalytic methods for organic synthesis is a topic of continuing interests. Biocatalysts which perform high reaction selectivity, mild reaction conditions, economically feasible, and potential use of inexpensive regenerable resources have been widely used in chemical, medicine, pesticide and other fields. Enzymes are efficient and green biocatalysts in synthetic chemistry. Not only "natural" reactions, other alternative reactions also can be catalyzed by enzymes, which were known as enzymatic promiscuity, and it has aroused wide concern of chemists. It is a significantly challenge to research enzymatic promiscuity, due to the limited type of enzyme in nature. It also greatly expands the application of existing enzymes and provides a green tool for organic synthesis.In this dissertation, we have studied the direct asymmetric aldol reaction catalyzed by enzyme. Here, this work described the direct asymmetric aldol reaction of aromatic aldehydes with cyclic or acyclic ketones catalyzed by proteinase from Aspergillus melleus (AMP) in organic medium, and YY-enzyme A coated the ionic liquid to catalyze the direct asymmetric aldol reaction. The effects of solvents, water contents, molar ratio between two substrates, enzyme concentration and temperature were explored on enzyme catalytic and stereoselective in the direct asymmetric aldol reaction catalyzed by AMP. A wide range of substrates could be transformed into the corresponding aldol products in yields up to89%, enantioselectivities up to91%ee and diastereoselectivities up to>99:1(antilsyn). A remarkable enhanced catalytic activity and enantioselectivity were obtained when the YY-enzyme A was coated with ionic liquid and used as catalyst for the direct asymmetric aldol reaction. And this work investigated the effect of different ionic liquids and the amount of ionic liquid on YY-enzyme A-catalyzed the direct asymmetric aldol reaction. We also studied the influence of solvents, water contents, molar ratio between two substrates, enzyme concentration and temperature on the YY-enzyme A was coated with ionic liquid and used as catalyst for the direct asymmetric aldol reaction. A wide range of substrates could be transformed into the corresponding aldol products in yields up to98%, enantioselectivities up to90%ee and diastereoselectivities up to>99:1(anti/syn).Biocatalytic Henry reaction was reported in this dissertation. YY-enzyme B as one of the biocatalysts which is environmental friendly, mild reaction conditions, economically feasible, could catalyze Henry reaction of aromatic aldehydes with nitroalkane. The effects of solvents, molar ratio between two substrates, enzyme loadings, phosphate buffer and temperature were investigated. Under the optimized conditions, YY-enzyme B can catalyze Henry reaction with a wide range of aromatic aldehyde and nitroalkane resulting in moderate to good yields, and the highest yield was92%. Unfortunately, YY-enzyme B-catalyzed Henry reaction failed to have the product with enantioselectivity, and further research is needed.In this dissertation, we also reported YY-enzyme B-catalyzed domino reaction to synthesis of2H-1-Benzopyran-2-one derivatives.2H-1-Benzopyran-2-one derivatives have good biological activity, anti-inflammatory, antioxidant, antiproliferative, sterilization, anticancer and regulating the central nervous system and other functions, which are widely used in the fields of medicine, food, spices, dyes, cosmetics and agricultural chemicals. And the synthesis of2H-1-Benzopyran-2-one derivatives attracted wide attention. Nevertheless, the traditional methods of synthesis of2H-1-Benzopyran-2-one derivatives have some defects, for instance, extreme conditions, excess of inorganic acid.2H-1-Benzopyran-2-one derivatives were synthesized by YY-enzyme B under mild conditions, and obtained yields between29%and87%.