(582ar) Impact of Sursfactants On Asymmetric Bioreduction of Aromatic Ketones Catalyzed By Yeast Cells

Chiral aromatic alcohols are important intermediates of pharmaceuticals, pesticides and other industrial chemicals. These chiral alcohols can be obtained from the asymmetric reduction of prochiral aromatic ketones catalyzed by yeast cells. Yeast cells are widely used due to their cheap and good reduction properties. For these asymmetric bioreduction, besides major effect factors, some additives can also change the reaction rate and selectivity, eventually affecting the substrate conversions and enantiomeric excesses. Surfactants are a kind of interesting additives because they can affect cell growth, metabolism, cell membrane permeability or intracellular enzyme activity. In this paper, the asymmetric reduction of aromatic ketones catalyzed by yeast cells were studied in presence of surfactants and the corresponding (S)-1-aryl-1-ethanols were obtained. The effects of surfactants on the conversion and enantiomeric excesses were investigated. The results indicated that the conversions could be remarkably affected and the enantiomeric excesses were less affected by the surfactants. The conversions of aromatic ketones (40 mmol/L) reached 95.7~99.0% in the system containing 0.5 g/L NP-4 (nonylphenol polyoxyethylene ether-4), exceeding 20% than the surfactant-free system. The enantiomeric excesses of product (S)-1-aryl-1-ethanols only changed 1~2 % in the reaction system with NP-4. The other surfactants were also applied for additives of asymmetric reduction of aromatic ketones. The results stated clearly that the nonionic surfactants were a kind of better additives than cationic surfactants or anionic surfactants in the asymmetric bioreduction of aromatic ketones catalyzed by yeast cells.