Bakers’ yeast reduces esters of 2-alkyl-3-oxobutanoic acid (CH3COCHRCO2R′; R=methyl, ethyl, propyl, propargyl, and allyl) into the corresponding (S)-hydroxy esters with exclusive stereoselectivity, while the configuration at the 2-position of the hydroxy esters is either S (anti) or R (syn) depending on the structure of the alkoxyl group in the carboalkoxyl moiety of the ester. Oftenly, the stereoselectivity
1,2-Asymmetric induction in radical reactions. Deuteration and allylation reactions of β-oxy-α-bromo esters
作者:Dennis P. Curran、P.S. Ramamoorthy
DOI:10.1016/s0040-4020(01)80402-6
日期:1993.5
Chiral radicals were generated by halogen abstraction reactions of β-oxy-α-bromo esters and their asymmetric deuteration and allylationreactions were studied.
通过β-氧基-α-溴代酸酯的卤素抽象反应生成手性自由基,并研究了它们的不对称氘代和烯丙基化反应。
CATALYST COMPONENT FOR OLEFIN POLYMERIZATION REACTION AND CATALYST THEREOF
申请人:China Petroleum & Chemical Corporation
公开号:EP1746110A1
公开(公告)日:2007-01-24
The present invention provides a catalyst component for polymerization of olefin CH2=CHR, in which R is hydrogen or C1-C12 alkyl or aryl, comprising magnesium, titanium, a halogen and an electron donor compound (a) which is at least one selected from the group consisting of dibasic ester compounds of the formula (I), and said catalyst component optionally further comprising an electron donor compound (b) selected from the group consisting of aliphatic dicarboxylic esters and aromatic dicarboxylic esters, and/or an electron donor compound (c) selected from the group consisting of 1,3-diether compounds of formula (IV):
wherein, R1, R' and A are as defined in the description,
wherein RI-RVIII are as defined in the description, and a catalyst comprising the catalyst component.
Influence of Cofactor Regeneration Strategies on Preparative-Scale, Asymmetric Carbonyl Reductions by Engineered <i>Escherichia coli</i>
作者:Dimitri Dascier、Spiros Kambourakis、Ling Hua、J. David Rozzell、Jon D. Stewart
DOI:10.1021/op400312n
日期:2014.6.20
This study was designed to determine whether whole cells or crude enzyme extracts are more effective for preparative-scale ketone reductions by dehydrogenases as well as learning which cofactor regeneration scheme is most effective. Based on results from three representative ketone substrates (an alpha-fluoro-beta-keto ester, a bis-trifluoromethylated acetophenone, and a symmetrical beta-diketone), our results demonstrate that several nicotinamide cofactor regeneration strategies can be applied to preparative-scale dehydrogenase-catalyzed reactions successfully.
NAKAMURA, KAORU;MIYAI, TAKEHIKO;NAGAR, ASHISH;OKA, SHINZABURO;OHNO, ATSUY+, BULL. CHEM. SOC. JAP., 62,(1989) N, C. 1179-1187