Bioreduction of methyl heteroaryl and aryl heteroaryl ketones in high enantiomeric excess with newly isolated fungal strains

Abstract: Enantioenriched heteroaryl ethanols and aryl heteroarylmethanols are important intermediates and structural motifs in medicinal chemistry. Asymmetric biocatalytic reduction of corresponding ketones provides a straightforward approach for preparation of these compounds. Accordingly, three newly isolated fungal strains have been described, which produced the desired heteroaryl alcohols in high enantiomeric excess (ee). A broad substrate specificity was observed within these limited number of biocatalysts as demonstrated by preparation of a variety of heteroaryl alcohols, including (S)-5-(1-hydroxyethyl)furo[2,3-c]pyridine, a key intermediate for HIV-1 reverse transcriptase inhibitor, (S)-phenyl(pyridin-2-yl)methanol, an analgesic and (S,S)-2,6-bis(1-hydroxyethyl)pyridine, a chiral building block, mostly in >99% ee and 80–92% yield. Micro-morphologically, one of the isolate was found to be similar to Penicillium funiculosum. However, its β-tubulin sequence showed only 88% sequence identity with the known β-tubulin sequences of Penicillium. It may, therefore, represent a new species of Penicillium. The other biocatalysts were identified as Alternaria alternata and Talaromyces flavus. [Copyright &y& Elsevier]