| This dissertation describes the application of S. carlsbergensis Old Yellow Enzyme (an NADPH dependent yeast oxidoreductase) in the biotransformation of different types of activated alkenes. Two classes of compounds, substituted cyclohexenones and beta-nitroacrylates, were synthesized and tested as potential substrates for OYE.;Both 2- and 3-substituted 2-cyclohexenones (5a-b and 9a-e) were shown to be reactive with the mentioned protein. Chemo- and stereoselective alkene reductions were observed and no alcohol products were detectable. In most of the cases, biotransformations proceeded with high optical purities, with the exception 2-exo-methylene cyclohexanones (13a-b), which were obtained as racemic mixtures. The enantioselectivities of the reactions were determined based on the chiral GC separation of the derivatized biotransformation products.;Enzymatic reductions of 2-substituted-beta-nitroacrylates (20c-f ) occurred with 87-96% of enantiomeric excess (e.e.), with larger substrates providing greater stereoselectivities. The products of the biotransformations were further chemically reduced to amino acid esters (22c-f) and derivatized with TFAA (trifluoroacetic anhydride) in order to assess the enantiomeric excess values. The acid hydrolysis of esters gave optically active beta 2-amino acids (23c-f), important drug intermediates and subjects of biological studies. In the case of 3-substituted-beta-nitroacrylates (20a-b), only racemic products were observed. |
