Enantioselective Dynamic Process Reduction of α- and β-Tetralone and Stereoinversion of Resulting Alcohols in a Selected Strain Culture

α-Tetralone and β-tetralone were subjected to biotransformation by 14 fungal strains. Enantiomeric purity of the products depended on the reaction time. 3-Day transformation of α-tetralone in Absidia cylindrospora culture gave S-(+)-1,2,3,4-tetrahydro-1-naftol of 92 % ee, whereas longer biotransformation time resulted in decrease of ee value. 3-Day transformation of β-tetralone by the same strain gave predominantly S-(−)-1,2,3,4-tetrahydro-2-naftol, whereas after 9 days of the reaction, the R-enantiomer with 85 % ee was isolated. Transformation of β-tetralone by Chaetomium sp. KCh 6651 gave pure (S)-(−)-1,2,3,4-tetrahydro-2-naftol in high yield at the concentration of 1 g/l. In this process, a non-selective carbonyl reduction was observed, followed by a selective oxidation of the R-alcohol

Enzymatic reactions of the C–C bond cleavage : applications in synthesis of aroma compounds, pharmaceuticals and in bioremediation

The microorganisms are able to utilize natural and synthetic compounds of broad structural diversity as a source of carbon and energy, converting these substrates into low molecular weight products (mainly H2O, CO2 and NH3). The main role in this metabolism is played by the enzymes that catalyze reactions of the C–C bond cleavage. Such reactions are the key step of the primary metabolism of fatty acids in eukaryotic cells by the β-oxidation. The enzymatic systems associated with the C–C bond cleavage have been applied in the synthesis of valuable natural products and in the bioremediation processes. Microbial transformations of natural compounds, in which the reactions of β-oxidation cycle are used, allow the formation of natural aromatic compounds (used as food additives), pharmaceuticals and ingredients of cosmetic compositions. Using this path one can obtain methyl ketones (e.g. responsible for the characteristic smell of cheeses), γ-lactones determining the scent of several popular fruits, and vanillin. A modification of the natural steroids: saponins, alkaloids, sterols, bile acids to products useful in the synthesis of steroid drugs is the most important area of use of the enzymatic C–C bond cleavage, due to the practical significance of the products. Enzymes that catalyze the C–C bonds cleavage are important in the process of biodegradation of toxic aromatic hydrocarbons and their derivatives (bioremediation)