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Synthesis of (S)-N-(2-Ethyl-6-methylphenyl) alanine by Enzyme-catalyzed Resolution and Chemical Racemization
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作者 ZHENG Liang-yu ZHANG Suo-qin +1 位作者 LU Xiao-li CAO Shu-gui 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2009年第6期836-840,共5页
A practical synthesis of (S)-N-(2-ethyl-6-methylphenyl)alanine, a key intermediate for (S)-metolachlor, was completed by means of lipase-catalyzed hydrolytic kinetic resolution and chemical racemization of the r... A practical synthesis of (S)-N-(2-ethyl-6-methylphenyl)alanine, a key intermediate for (S)-metolachlor, was completed by means of lipase-catalyzed hydrolytic kinetic resolution and chemical racemization of the remaining ester. The effects of operating temperature and enzyme concentration on the activity and enantioselectivity of enzyme were initially studied, and it was found that the enantioselectivity of CAL-B towards the resolution was not high enough to obtain enantiomerically pure compound(E=12.1). When diethyl ether(15%, volume fraction) was added in the reaction medium, the lipase gave an excellent enantioselectivity(E=117.8), which is about 9.7-fold that in pure buffered aqueous solution. For overcoming the limitation of a maximum theoretical yield of 50%, the acid product was separated from the remaining ester by a simple extraction procedure and the remaining ester was racemized with aldehyde and acetic acid under microwave irradiation or conventional heating condition, The results show the microwave irradiation was more effective than the conventional heating method and gave the desired (R,S)-N-(2- ethyl-6-methylphenyl)alanine methyl ester a high yield(92%) with R/S=50/50 in 1 h. 展开更多
关键词 Candida antarctica lipase B REsOLUTION (s)-N-(2-ethyl-6-methylphenyl)alanine RACEMIZATION
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Microtropins J-P: 6’-O-(2”<i>S</i>,3”<i>R</i>)-2”-Ethyl-2”,3”-Dihydroxybutyrates of Phenolic Alcohol <i>&#223</i>-D-Glucopyranosides from the Branches of <i>Microtropis japonica</i>
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作者 Yuka Uemura Sachiko Sugimoto +2 位作者 Katsuyoshi Matsunami Hideaki Otsuka Yoshio Takeda 《American Journal of Plant Sciences》 2013年第10期1954-1959,共6页
From the branches of Microtropis japonica (Celastraceae), seven phenolic alcohol glucosides, named microtropins J-P (1-7), were isolated. The 6-position of glucose was esterified with 2-ethyl-2,3-dihydroxybutyric acid... From the branches of Microtropis japonica (Celastraceae), seven phenolic alcohol glucosides, named microtropins J-P (1-7), were isolated. The 6-position of glucose was esterified with 2-ethyl-2,3-dihydroxybutyric acid. Microtropin K (2) was hydrolyzed under a mild basic condition to give methyl (2S,3R)-2-ethyl-2,3-dihydroxybutyrate, whose absolute structure was determined by the comparison of NMR data and the optical rotation value with that reported. 展开更多
关键词 Microtropis JAPONICA CELAsTRACEAE Microtropin (2s 3R)-2-ethyl-2 3-Dihydroxybutyrate
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Utilization of One Novel Microbial Esterase WDEst9 in the Kinetic Resolution of (5)-Methyl 2-chloropropionate and (5)-Ethyl 2-chloropropionate 被引量:2
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作者 WANG Yilong XU Yongkai +2 位作者 ZHANG Yun SUN Aijun HU Yunfeng 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2019年第5期830-836,共7页
One novel microbial esterase WDEst9 from Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085 was functionally characterized and the results demonstrated that the enantio-preference of WDEst9 was opposite to th... One novel microbial esterase WDEst9 from Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085 was functionally characterized and the results demonstrated that the enantio-preference of WDEst9 was opposite to that of three other microbial esterases(BSE01701, PHE14 and Bae02030) in the kinetic resolution of racemic methyl lactate. We further investigated the potential of esterase WDEst9 in the kinetic resolution of both (±)-methyl 2-chloropropionate and (±)-ethyl 2-chioropropionate. The enantio-preference of WDEst9 was also interestingly opposite to that of esterases EST 12-7 and EstC10, and generated (S)-methyl 2-chloropropionate and (S)-ethyl 2-chloropropionate with high enantiomeric excess(both e.e.>98%) and high yield after many iterations of process optimization. Through genome mining, microbial esterase WDEst9 was characterized to be a novel esterase which may provide valuable complementary enantio-selectivity and possesses very good potential in the kinetic resolution of high value-added chiral chemicals. 展开更多
关键词 BIOCATALYsIs NOVEL EsTERAsE Asymmetric HYDROLYsIs Complementary enantio-preference (5)-Methyl 2-chloropropionate (s)-Ethyl 2-chloropropionate
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