| In this dissertation, a series of syntheticβ-tert-Hydroxyl Esters / Nitriles /Acids were used as test samples for optical purity assay. Subsequently, the preliminary studies in enzymatic hydrolysis ofβ-tert-Hydroxyl Esters were carried on.In Chapter One, the features, necessity of separation and sources of chiral compound, and bioactivities ofβ-tert-Hydroxy Esters / Nitriles were reviewed, Chirality is one of nature's essences and the basic property of three-dimensional objects. Just like human hands, which can't superimpose each other, are kind of the mirror relationship. Compounds with such relations are called "enantiomers".The existence of enantiomers is the process of a common phenomenon in nature and chemical synthesis. Optically active natural substances are widely found in animals and plants. As we know, the natural configuration of sugar is D-type; amino acids L-type; proteins and DNA's helices also D-type. All of those mentioned above are the unique biological instinct. Enantiomers existed in drugs, pesticides and taste compounds show different biological responses in life system.A convenient method to obtain optically active isomer is racemic separation. It requires a short-cycle and is widely used in the industrial production. Physical separation (crystallization), chemical separation, biological separation (enzymatic separation), and chromatographic separation are the main methods in racemic separation. The advantages of biological separation are high selectivity, mild reaction condition, high tolerance to substrates, variable reaction types, absence of heavy metal catalysts, occurrence of multiple side effects, and so on, in accordance with the conception of green chemistry. Chromatographic separation is also known for its high sensitivity and reliability.Chiral tertiary alcohols are important structural units present in many natural products and drugs.β-tert-hydroxy esters/ nitriles as important synthetic intermediates can be further used for synthesis of a series of useful antibiotics, HMG-CoA reductase inhibitors, pheromones, and many other drugs and agricultural chemicals by the transformation of functional groups.In Chapter Two,β-tert-hydroxyl-esters /nitriles were synthesized via acetate aldol Reaction. The two useful strategies for construction of chiral tertiary alcohols are Reformatsky Reaction and acetate aldol reactions. After comprehensive consideration in catalyst preparation, reaction conditions and cost, we decided to use acetate aldol reaction to synthesize the target compounds. In the compounds design, we took into account of the electronic effects and steric impact. All of target products were obtained with high yields (> 70%). However, the similar approach toβ-tert-hydroxy nitriles resulted in significant recovery of start materials (up to 46%). This problem was solved by application of anhydrous cerium chloride to promote the acetate aldol reaction.In Chapter Three, measurement of the optical purity ofβ-tert-hydroxy esters/ nitriles/ acid was investigated by chiral HPLC.β-tert-hydroxy esters were hydrolyzed under catalytic KOH to produce the racemicβ-tert-hydroxy acids. In the reverse phase HPLC, chiral stationary phase (Chiral-AGP,OD-RH), pH value, mobile phase composition and changes in the proportion of mobile phase were all tested to optimize the resolution efficiency. Chiral-AGP can separate four racemicβ-tert-hydroxy esters, threeβ-tert-hydroxy acids, sevenβ-tert-hydroxy nitriles; OD-RH can separate threeβ-tert–hydroxyl esters,β-tert-hydroxy acids. The resolution (all above1.5) meets the need of the separation requirements. These optical purity assay methods lay a foundation for subsequent enzymatic hydrolysis. In Chapter Four, the preliminary studies on enzymatic hydrolysisβ-tert-hydroxy Esters were carried on. Enantiomeric ratio (E) was selected as an important parameter to evaluate enzymatic hydrolysis reaction. E value calculation is related with conversion and optical purity of product or starting material. To guarantee the accuracy and precision, external standard method was chosen to calculate the reaction conversion. Meanwhile, combinatorial chemistry strategy was used in the purpose of improving screening efficiency. In the enzymes activity screening,Eight commercial enzymes was screened to eightβ-tert-hydroxyl-esters,only lipase CAL-A has selectivity to compound 2-2b ( Ethyl 3-(benzyloxy)-3-hydroxy-butanoate ) .So compound 2-2b and enzyme CAL-A was selected as couonterpart. Fourteen co-solvents and the concentrateion of co-solvent were screened in the optimization.In the solvent screening, it was found that the hydrophilic solvent for the reaction selectivity was significantly higher than hydrophobic solvents. However, the reaction rate is higher in hydrophobic solvents than in hydrophilic solvents.In the solvent concentration screening, the results of solvent screening were used as reference (E> 10 as boundary).It was shown that decreasing the content of organic solvents led to improvement of the selectivity and the rate of reaction, but in the absence of organic solvents, enantiomeric ratio is only 13.6 (not a significant change).In summary, when the enzyme is CAL-A in 20% of organic solvent dioxane, E value is 15.9 (the best result).
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