How Substrate Solvation Contributes to the Enantioselectivity of Subtilisin toward Secondary Alcohols
摘要:
The current rule to predict the enantiopreference of subtilisin toward secondary alcohols is based on the size of the substituents at the stereocenter and implies that the active site contains two differently sized pockets for these substituents. Several experiments are inconsistent with the current rule. First, the X-ray structures of subtilisin show there is only one pocket (the S1' pocket) approximately the size of a phenyl group to bind secondary alcohols. Second, the rule often predicts the incorrect enantiomer for reactions in water. To resolve these contradictions, we refine the current rule to show that subtilisin binds only one substituent of a secondary alcohol and leaves the other in solvent. To test this refined empirical rule, we show that the enantioselectivity of a series of secondary alcohols in water varied linearly with the difference in hydrophobicity (log P/P0) of the substituents. This hydrophobicity difference accounts for the solvation of one substituent in water.
Iron-catalyzed asymmetric hydrosilylation of ketones
作者:Ziqing Zuo、Lei Zhang、Xuebing Leng、Zheng Huang
DOI:10.1039/c5cc00612k
日期:——
iminopyridine-oxazoline (IPO) ligands have been synthesized. The most sterically hindered iron catalyst exhibits excellent activity (up to 99% yield) and high enantioselectivity (up to 93% ee) in asymmetrichydrosilylation of aryl ketones.
Highly Enantioselective Addition of Me<sub>2</sub>Zn to Aldehydes Catalyzed by ClCr(Salen)
作者:Pier Giorgio Cozzi、Peter Kotrusz
DOI:10.1021/ja057969d
日期:2006.4.1
enantiomeric excesses are obtained in the addition of Me2Zn catalyzed by commercially available ClCr(Salen). Broad scope, simple procedure, room temperature, low catalyst loading are the characteristics of this new enantioselective process, which uses the rather unreactive Me2Zn. Enantiomeric excesses in the range of 71-99% are obtained with all the aldehydes tested.
Studies on Rhizopus arrhizus mediated enantioselective reduction of arylalkanones
作者:Neeta A Salvi、Subrata Chattopadhyay
DOI:10.1016/s0040-4020(01)00134-x
日期:2001.4
The effect of substitution on the biotransformation of various arylalkanones using Rhizopus arrhizus was investigated. The organism was found to be promising for the reduction of phenylalkanones and arylethanones with good to excellent enantioselectivity. The reduction followed Prelog's rule giving the (S)-carbinols in all the cases. The enantioselectivity of the reaction improved with increasing size
Titanium complex of fluorous axially dissymmetric ligand ((Ra∗)-2,2′-bis[(R∗)-perfluoro-1H-1-hydroxyoctyl]biphenyl, ((Ra∗)-(R∗)2-1)) having perfluoroheptyl carbinol moieties catalyzedenantioselectiveaddition of a methyl group to aldehydes. Dimethylzinc prepared in situ by mixing ZnCl2 and methyl magnesium bromide without removal of magnesium salt was more reactive for addition of methyl group than
Activity and specificity studies of the new thermostable esterase EstDZ2
作者:Kamela Myrtollari、Nikolaos Katsoulakis、Dimitra Zarafeta、Ioannis V. Pavlidis、Georgios Skretas、Ioulia Smonou
DOI:10.1016/j.bioorg.2020.104214
日期:2020.11
In this paper, we study the activity and specificity of EstDZ2, a new thermostable carboxyl esterase of unknown function, which was isolated from a metagenome library from a Russian hot spring. The biocatalytic reaction employing EstDZ2 proved to be an efficient method for the hydrolysis of aryl p-, o- or m-substituted esters of butyric acid and esters of secondary alcohols. Docking studies revealed