| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1344925 | Tetrahedron: Asymmetry | 2008 | 5 Pages |
The use of whole cells of micro-organisms to bring about the biotransformation of an organic compound offers a number of advantages, but problems caused by enzymatic promiscuity may be encountered upon with substrates bearing more than one functional group. A one-pot screening method, in which whole fungal cells were incubated with a mixture of 4-methylcyclohexanone 1 and phenyl methyl sulfide 2, has been employed to determine the chemoselectivity of various biocatalysts. The hyphomycetes, Aspergillus terreus CCT 3320 and A. terreus URM 3571, catalysed the oxidation of 2 accompanied by the reduction of 1 to 4-methylcyclohexanol 1a and, for strain A. terreus CCT 3320, the Baeyer-Villiger oxidation of 1. The Basidiomycetes, Trametes versicolor CCB 202, Pycnoporus sanguineus CCB 501 and Trichaptum byssogenum CCB 203, catalysed the oxidation of 2 and the reduction 1, but no Baeyer–Villiger reaction products were detected. In contrast, Trametes rigida CCB 285 catalysed the biotransformation of 1 to 1a, exclusively, in the absence of any detectable sulfide oxidation reactions. The chemoselective reduction of (±)-2-(phenylthio)cyclohexanone 3 by T. rigida CCB 285 afforded exclusively the (+)-cis-(1R,2S) and (+)-trans-(1S,2S) diastereoisomers of 2-(phenylthio)cyclohexan-1-ol 3a in moderate yields (13% and 27%, respectively) and high enantiomeric excesses (>98%). Chemoselective screening for the reduction of a ketone and/or the oxidation of a sulfide group in one pot by whole cells of micro-organisms represents an attractive technique with applications in the development of synthesis of complex molecule bearing different functional groups.
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(+)-cis-(1R,2S)-2-(Phenylthio)-1-cyclohexanolC12H16OSEe = >98%[α]D25=+19.7 (c 0.42, CH2Cl2)Absolute configuration: (1R,2S)
(+)-trans-(1S,2S)-2-(Phenylthio)-1-cyclohexanolC12H16OSEe = >98%[α]D25=+61.0 (c 0.44, CH2Cl2)Absolute configuration: (1S,2S)
