Preparation of both enantiomers of an α-hydroxy ketone via biocatalytic reduction and chemical oxidation
1993; Elsevier BV; Volume: 15; Issue: 6 Linguagem: Inglês
10.1016/0141-0229(93)90080-l
ISSN1879-0909
AutoresMahima Negi, Gottumukkala V. Subbaraju, M. S. MANHAS, Ajay K. Bose,
Tópico(s)Steroid Chemistry and Biochemistry
Resumo2-Hydroxy-2,6,6-trimethylcyclohexanone 1 is a key intermediate for the synthesis of naturally occurring bioactive metabolites, viz. 2A-B and 3. Both enantiomers of this key intermediate 1 were obtained by sterospecific reduction using Bakers' yeast under nonfermenting conditions followed by chemical oxidation. Free as well as immobilized cells were tested in aqueous and organic media for their ability to catalyze the sterospecific reduction of the parent ketone 1. Preparative scale biotransformation of 1 in aqueous medium using free cells of Bakers' yeast produced two diastereomeric alcohols 4 and 5 at a ratio of approximately 1 :4 and 9.1% and 36.4% chemical yields, respectively. The reduced products exhibited high enantiomeric excess (>90%) as analyzed by 1H and 13C-NMR spectroscopy. Unreduced hydroxy ketone was found to be highly enriched in S (−)-1, while chemical oxidation of the diol 5 gave R (+) 1. A reversal of diastereoselectivity was observed when an organic medium was used for biotransformation.
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