- Access to Optically Enriched α-Aryloxycarboxylic Esters via Carbene-Catalyzed Dynamic Kinetic Resolution and Transesterification
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Optically active α-aryloxycarboxylic acids and their derivatives are important functional molecules. Disclosed here is a carbene-catalyzed dynamic kinetic resolution and transesterification reaction for access to this class of molecules with up to 99% yields and 99:1 er values. Addition of a chiral carbene catalyst to the ester substrate leads to two diastereomeric azolium ester intermediates that can quickly epimerize to each other and thus allows for effective dynamic kinetic resolution to be realized. The optically enriched ester products from our reaction can be quickly transformed to chiral herbicides and other bioactive molecules.
- Liu, Bin,Song, Runjiang,Xu, Jun,Majhi, Pankaj Kumar,Yang, Xing,Yang, Song,Jin, Zhichao,Chi, Yonggui Robin
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supporting information
p. 3335 - 3338
(2020/04/30)
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- Optical resolution of aryloxypropionic acids and their esters by HPLC on cellulose tris-3,5-dimethyl-triphenylcarbamate derivative
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Chiral chromatographic resolution of a series of antiphlogistic 2- aryloxypropionic acids and their methyl and ethyl esters was performed using a Chiralcel OD column. The CSP selected resolved most of the acids and esters efficiently, the enantiomers being well separated without requiring time consuming analysis. Chromatographic separation of R enriched samples was performed to determine the correct elution order. Using eluting systems such as hexane and 2-propanol, or hexane, 2-propanol and formic acid, the S enantiomer of all acids and esters was always found to elute first. We also considered the role of electron-donating or electron-withdrawing substituents (at the aryloxylic moiety) on the chiral resolution. It was shown that the electronic features of the substituents have more influence on the chiral interactions between the solutes and the CSP than their steric hindrance. Finally we determined, by molecular models, the interaction between CSP and solutes. In this way were able to determine all the potential sites for interactions, which are compatible with the conformations of the compounds and the structure of the stationary phase, and point out those interactions which enable chiral resolution.
- Azzolina,Collina,Ghislandi
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p. 1401 - 1416
(2007/10/02)
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- Antiphlogistic aryloxypropionic acids: Configurational study
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Configurational relationships of a series of antiphlogistic 2-aryloxypropionyl derivatives by means of 1H-NMR and HPLC methods were demonstrated. NMR spectra of racemic mixtures and optically active esters were recorded by adding suitable quant
- Azzolina,Ghislandi
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p. 713 - 724
(2007/10/02)
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