Biocatalytic hydrogen-transfer reduction of a-chloro-ketones furnished non-racemic chlorohydrins by employing either Rhodococcus ruber as lyophilized cell catalyst or an alcohol dehydrogenase preparation from Pseudomonas fluorescens DSM 50106 (PF-ADH). For all substrates investigated, Rhodococcus ruber gave strictly the "Prelog" product, whereas PF-ADH showed scattered stereopreference. One possibility for a follow-up reaction of halohydrins is the ring closure to the corresponding epoxide.A novel "one pot-one step strategy" was employed to obtain the enantiopure epoxide from the a-chloro-ketone in a cascade like fashion at pH > 12 involving biocatalytic hydrogen transfer reduction and in situ chemo-catalyzed ring closure.

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Biochemical syntheses O 0035Asymmetric anti-Prelog Reduction of Ketones Catalyzed by Paracoccus pantotrophus and Comamonas sp. Cells via Hydrogen Transfer. -Isopropanol is used as a hydrogen source for the conversion of a wide range of cyclic and linear, aromatic and aliphatic ketones to the corresponding alcohols. Ketones containing α-ester groups are hydrogenated selectively [cf. (Xb)]. -(LAVANDERA, I.; HOELLER, B.; KERN, A.; ELLMER, U.; GLIEDER, A.; DE WILDEMAN, S.; KROUTIL*, W.; Tetrahedron: