Asymmetric microbial reduction of ketones: absolute configuration of trans-4-ethyl-1-(1S-hydroxyethyl)cyclohexanol

Abstract

a b s t r a c tA set of five fungal species, Botrytis cinerea, Trichoderma viride and Eutypa lata, and the endophytic fungi Colletotrichum crassipes and Xylaria sp., was used in screening for microbial biocatalysts to detect monooxygenase and alcohol dehydrogenase activities (for the stereoselective reduction of carbonyl compounds). 4-Ethylcyclohexanone and acetophenone were biotransformed by the fungal set. The main reaction pathways involved reduction and hydroxylations at several positions including tertiary carbons. B. cinerea was very effective in the bioreduction of both substrates leading to the chiral alcohol (S)-1-phenylethanol in up to 90% enantiomeric excess, and the cis-trans ratio for 4-ethylcyclohexanol was 0:100. trans-4-Ethyl-1-(1S-hydroxyethyl)cyclohexanol, obtained from biotransformation by means of an acyloin-type reaction, is reported here for the first time. The absolute configurations of the compounds trans-4-ethyl-1-(1S-hydroxyethyl)cyclohexanol and 4-(1S-and 4-(1R-hydroxyethyl)cyclohexanone were determined by NMR analysis of the corresponding Mosher's esters.

Prevalence and specificity of Baeyer–Villiger monooxygenases in fungi

“…Fungi offer the great advantage of being equipped with many constitutive enzymes and not needing any inducer. Nevertheless, several screening experiments failed to identify microorganisms capable of BV oxidation (Carballeira et al, 2004;Pinedo-Rivilla et al, 2009). The present work owes its success mainly to two additional elements: duration of growth and choice of substrate.…”

Chemical, diversity and biotechnological potential of endophytic fungi isolated from Brazilian Cerrado plants

“…In order to detect monooxygenase and alcohol dehydrogenase activity, Pinedo-Rivilla et al (2009) studied the biotransformation of pro-chiral ketones (4-ethylcyclohexanone and acetophenone) by filamentous fungi and endophytic fungi isolated from Casearia sylvestris. The analyses showed the biocatalytic potential for obtaining biotransformation compounds with high enantiomeric purity.…”

Endophytic Fungi From the Brazilian Flora and Their Employment in Biotransformation Reactions

“…yielded the metabolites 4-ethyl-4-hydroxycyclohexanone (8d) and 4-(1R-hydroxyethyl) cyclohexanone (8e), after 10 days of incubation. 32 The optically pure chiral amines are also important starting materials for organic synthesis. Among the methods for obtaining such amines, the use of ω-transaminase in biocatalytic processes has emerged as promising strategy.…”