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Sequential deracemization of sulfoxides via whole-cell resolution and heterogeneous oxidation

Paper ID Volume ID Publish Year Pages File Format Full-Text
40771 45865 2012 5 PDF Available
Title
Sequential deracemization of sulfoxides via whole-cell resolution and heterogeneous oxidation
Abstract

A new concept for the synthesis of asymmetric sulfoxides exploiting sequential deracemization of racemic (rac) sulfoxides using a two-stage protocol had been developed. Enantio-pure sulfoxide was obtained using Escherichia coli (E. coli) cells to catalyze the reduction of (R)-sulfoxide to the thioether, and then using a heterogeneous Ta2O5–SiO2 catalyst for catalyzing the oxidation of the ethers to the rac-sulfoxide. The performance of E. coli depended on the strain and the conditions under which the bacteria growth was carried out (e.g. source of carbon, presence of vitamins, and concentration of dimethyl sulfoxide, DMSO). Under optimized conditions, the E. coli cells performed the rac-sulfoxide resolution for different sufoxides leading to the best enantiomeric excess (ee) of around 62% (S)-MTSO (methyl tolyl sulfoxide) with 49% conversion of the rac-MTSO. The sequential deracemization process applied for rac-MTSO was cyclically performed leading to 97.5% ee of (S)-sulfoxide and a 56% yield in (S)-sulfoxide after three deracemization cycles of rac-MTSO.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (230 K)Download as PowerPoint slideHighlights► Enantioreduction of rac-sulfoxide was performed using Escherichia coli biocatalyst. ► Optimum growth conditions of E. coli biocatalyst have been set up. ► Selectivity of the biocatalyst was tested for different rac-sulfoxides. ► Sequential two-step deracemization was performed for rac-sulfoxides.

Keywords
Sequential deracemization; Racemic sulfoxides; Escherichia coli; Enantioselective reduction; Selective heterogeneous oxidation
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Sequential deracemization of sulfoxides via whole-cell resolution and heterogeneous oxidation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 441–442, 28 October 2012, Pages 42–46
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
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Price after discount Only $4.95
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