Complexes prepared in situ from RuCl 2 (PPh 3 ) 3 and chiral phosphine-oxazoline ligands are effective catalysts for the hydrogenation of various aryl ketones with ees up to 99% and substrate to catalyst ratios of 10,000 -50,000; the reaction tolerates high substrate concentrations and a pilot process has been developed for the hydrogenation of 3,5-bistrifluoromethyl acetophenone.

Phage display can be used as a protein‐engineering tool for the selection of proteins with desirable binding properties from a library of mutants. Here we describe the application of this method for the directed evolution of Bacillus subtilis lipase A, an enzyme that has important properties for the preparation of the pharmaceutically relevant chiral compound 1,2‐O‐isopropylidene‐sn‐glycerol (IPG). PCR mutagenesis with spiked oligonucleotides was employed for saturation mutagenesis of a stretch of amino acids near the active site. After expression of these mutants on bacteriophages, dual selection with (S)‐(+)‐ and (R)‐(−)‐IPG stereoisomers covalently coupled to enantiomeric phosphonate suicide inhibitors (SIRAN Sc and Rc inhibitors, respectively) was used for the isolation of variants with inverted enantioselectivity. The mutants were further characterised by determination of their Michaelis–Menten parameters. The 3D structures of the Sc and Rc inhibitor–lipase complexes were determined and provided structural insight into the mechanism of enantioselectivity of the enzyme. In conclusion, we have used phage display as a fast and reproducible method for the selection of Bacillus lipase A mutant enzymes with inverted enantioselectivity.

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The esterase-catalyzed enantioselective hydrolysis of the fluoroacetate of pantolactone leads to fluoroacetic acid, a toxic compound which inhibits the growth of esterase-producing yeast; this forms the basis of an ee-assay.