Enantioselective Hydrolysis of Some 2-Aryloxyalkanoic Acid Methyl Esters and Isosteric Analogues Using a Penicillin G Acylase-Based HPLC Monolithic Silica Column
A technique based on liquid chromatography has been developed to facilitate studies of enantioselectivity in penicillin G acylase (PGA)-catalyzed hydrolysis of some 2-aryloxyalkanoic acid methyl esters and isosteric analogues. PGA was covalently immobilized on an aminopropyl monolithic silica support to create an immobilized HPLC-enzyme reactor. Two sets of experimental data were drawn to calculate the enantioselectivity (E) of the kinetically controlled enantiomer-differentiating reaction, the degree of substrate conversion and the enantiomeric excess of the product. The developed enzymatic reactor was coupled through a switching valve to an achiral analytical column for separation and quantitation of the hydrolysis products. The enantiomeric excess was determined off-line on a PGA-chiral stationary phase. In this way, highly precise E values were determined. A computational study related to the hydrolysis of the considered racemic esters was also carried out in order to unambiguously clarify both the substrate specificity and the enantioselectivity displayed by PGA.
Diradicals Photogeneration from Chloroaryl‐Substituted Carboxylic Acids
作者:Lorenzo Di Terlizzi、Stefano Protti、Davide Ravelli、Maurizio Fagnoni
DOI:10.1002/chem.202200313
日期:2022.5.6
With the aim of generating new, thermally inaccessible diradicals, potentially able to induce a double-strand DNA cleavage, the photochemistry of a set of chloroaryl-substituted carboxylicacids in polar media was investigated. The photoheterolytic cleavage of the Ar-Cl bond occurred in each case to form the corresponding triplet phenyl cations. Under basic conditions, the photorelease of the chloride
为了产生新的、热难以接近的双自由基,可能能够诱导双链 DNA 切割,研究了一组氯芳基取代的羧酸在极性介质中的光化学。在每种情况下都发生 Ar-Cl 键的光异解裂解以形成相应的三重态苯基阳离子。在碱性条件下,氯阴离子的光释放伴随着从羧酸根到芳族自由基阳离子位点的分子内电子转移,形成双自由基。根据所得双自由基的稳定性,后一种中间体可能会以结构依赖的方式经历 CO2 损失,或从介质中提取氢原子。在生理 pH 值 (pH=7.3) 的水环境中,观察到苯基阳离子和双自由基化学。
[EN] NICOTINAMIDE DERIVATIVES<br/>[FR] DÉRIVÉS DE NICOTINAMIDE
申请人:PFIZER LTD
公开号:WO2009153721A1
公开(公告)日:2009-12-23
The present invention relates to compounds of the formula (I) and pharmaceutically acceptable salts and solvates thereof, wherein the substituents are defined herein, to compositions containing such compounds and to the uses of such compounds for the treatment of allergic and respiratory conditions.
Transition metal-cyclopentadienyl-tropane conjugate compounds are described. Methods for preparing transition metal-cyclopentadienyl-tropane conjugate compounds are also described. Transition metal-cyclopentadienyl-tropane conjugate compounds of the invention exhibit an affinity for monoamine transporters and are useful as diagnostic and/or therapeutic agents.
The present invention relates to compounds of the formula (I) and pharmaceutically acceptable salts and solvates thereof, wherein the substituents are defined herein, to compositions containing such compounds and to the uses of such compounds for the treatment of allergic and respiratory conditions.