GC Separation of Enantiomers of Alkyl Esters of 2-Bromo Substituted Carboxylic Acids Enantiomers on 6-TBDMS-2,3-di-alkyl- β- and γ-Cyclodextrin Stationary Phases
作者:Ivan Špánik、Darina Kačeriaková、Jan Krupčík、Daniel Wayne Armstrong
DOI:10.1002/chir.22310
日期:2014.6
The gas chromatographic separation of enantiomers of 2‐Br carboxylicacid derivatives was studied on four different 6‐TBDMS‐2,3‐di‐O‐alkyl‐ β‐ and ‐γ‐CD stationaryphases. The differences in thermodynamic data ΔH and –ΔS} for the 15 structurally related racemates were evaluated. The influence of structure differences in the alkyl substituents covalently attached to the stereogenic carbon atom, as
Enoate Reductase-Mediated Preparation of Methyl (<i>S</i>)-2-Bromobutanoate, a Useful Key Intermediate for the Synthesis of Chiral Active Pharmaceutical Ingredients
作者:Elisabetta Brenna、Francesco G. Gatti、Alessia Manfredi、Daniela Monti、Fabio Parmeggiani
DOI:10.1021/op200086t
日期:2012.2.17
Enoate reductases belonging to the Old Yellow Enzyme (OYE) family were employed to develop a biocatalysed approach to methyl (S)-2-bromobutanoate, a key intermediate for the introduction of a particular stereogenic unit into the molecular skeleton of a certain class of chiral drugs. Methyl (Z)-2-bromocrotonate afforded, respectively, (S)-2-bromobutanoic acid (ee = 97%) and methyl (S)-2-bromobutanoate (ee = 97%) by baker's yeast fermentation and by OYE1-3 biotransformations. The bioreductions of other methyl 2-haloalkenoates were also considered. It was observed that the (Z)- and (E)-diastereoisomers of alpha-bromo unsaturated esters afforded the same enantiomer of the corresponding reduced product.