Expanding the Scope of Alcohol Dehydrogenases towards Bulkier Substrates: Stereo- and Enantiopreference for a,a- Dihalogenated Ketones

KINGA KEDZIORA; FABRICIO R. BISOGNO; IVÁN LAVANDERA; VICENTE GOTOR-FERNÁNDEZ; JOSÉ MONTEJO-BERNARDO; SANTIAGO GARCÍA-GRANDA; WOLFGANG KROUTIL; VICENTE GOTOR

CHEMCATCHEM

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2014 vol. 6 p. 1066 - 1072

1867-3880

Alcohol dehydrogenases (ADHs) were identified as suitable enzymesfor the reduction of the corresponding a,a-dihalogenatedketones, obtaining optically pure b,b-dichloro- or b,b-dibromohydrinswith excellent conversions and enantiomericexcess. Among the different biocatalysts tested, ADHs fromRhodococcus ruber (ADH-A), Ralstonia sp. (RasADH), Lactobacillusbrevis (LBADH), and PR2ADH proved to be the most efficientones in terms of activity and stereoselectivity. In a furtherstudy, two racemic a-substituted ketones, namely a-bromo-achloro-and a-chloro-a-fluoroacetophenone were investigatedto obtain one of the four possible diastereoisomers througha dynamic kinetic process. In the case of the brominated derivative,only the (1R)-enantiomer was obtained by using ADH-A,although with moderate diastereomeric excess (>99% ee,63% de), whereas the fluorinated ketone exhibited a lowerstereoselectivity? (up to 45% de).