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Chloroperoxidase catalyzed asymmetric synthesis of chiral building block C_3~-

Author: WangYaLi
Tutor: JiangYuCheng
School: Shaanxi Normal University
Course: Inorganic Chemistry
Keywords: Chloroperoxidase Chiral intermediates 2,3-dichloro-1-propanol glycidol 3-chloro-1,2-propanediol
CLC: O621.36
Type: Master's thesis
Year: 2012
Downloads: 38
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Abstract


The C3-and C4-small organic molecule with optical activity is an important intermediate for the pharmaceuticals and fine chemical products as well as the raw material for a variety of synthesis organic compounds. In order to obtain chiral intermediates with good optical activity, a great number of studies have been made and the synthesis process has been developed continuously. While the synthetic method is the use of biological enzymes for the stereospecific selective catalyst and the asymmetric synthesis of optically active substances are the most promising ones.Chloroperoxidase (CPO) with a wide variety of catalytic properties because of its unique active site structure is now considered as the most widely used enzyme in the heme-peroxidase family. It not only has a wide range of adaptability to the substrate, but also has the function of chiral recognition, eg. synthetizing chiral intermediate or chiral drug through hydroxylation, oxidation or epoxidation. Pure CPO is very stable, and can be stored for2to3years without losing active in4℃environment, so it has prosperous application as a biological catalyst.The study used the small molecule chloropropene, allyl alcohol, bromomethyl cyclopropane as the substrate, researched the synthetizing a series of C3-chiral block of with CPO as the catalyst through the qualitative analysis by Gas Chromatography-Mass Spectrometry(GC-MS) and the method of NMR spectroscopy, and the quantitative analysis of the products using Gas Chromatography internal standard method and standard curve method, calculated the product yield and enantioselectivity (e.e. value), at the same time the various factors affecting the reaction were investigated. The results are as follows:1. Under the Cl" existing conditions, the products of catalytic asymmetric chloropropene chloride hydroxylation was R-2,3-dichloro-l-propanol, the system was mainly affected by the amount of oxidant, the dosage of enzyme, pH value, reaction time and other factors. When added the Imidazole Ion liquid ([EMIM][Br].[PMIM][Br].[BMIM][Br].[AMIM][Br]) for the co-solvent, Which [EMIM][Br] a significant effect, under optimal conditions, the yield and enantioselectivity were64.8%and98.1%respectively, the amount of enzyme was only0.2μmol, and the reaction time was8h.2. Using allyl alcohol as substrate, the products of CPO catalytic epoxidation synthesis was R-2,3-epoxy-l-propanol (glycidol), chloride hydroxylation synthesis was R-3-chloro-1-2-propanediol. The system was mainly affected by oxidants, enzyme dosage, pH value, reaction time and other factors. After introduction of imidazole ionic liquid as co-solvent, The final yield could reach40.8%and84.7%, and enantioselectivity were96.7%and97.5%respectively by the R-3-chloro-1-2-propanediol and R-2,3-epoxy-1-propanol. Very few amount of enzyme were0.05μmol and0.075μmol, The reaction time are5h and3.5h respectively. The yield of glycidol were low because in the case of the enolate used as substrate, the CPO used as catalyst, the reaction were generally difficult to process. At the same time glycidyl in acid, base or salt could self polymerization. Through the reaction of allyl alcohol could been seen the diversity of the CPO catalytic reaction.3. In the case of bromomethyl cyclopropane used as substrate, CPO catalyzed oxidation the synthesis of C4-building block has been studied. The characterized analysis result of the purified product was to finalize which was also an important organic synthetic raw materials, could also be used for synthetic drugs. The system had been optimized, the yield reached59.2%, reaction time2h and the amount of enzyme was0.35μmol.

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CLC: > Mathematical sciences and chemical > Chemistry > Organic Chemistry > Organic Chemistry general issues > Synthetic organic chemistry > Heavy organic synthesis or catalytic organic synthesis
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