ORGN 791 |
| The biocatalytic anti−Prelog stereoselective reduction of acetyltrimethylsilane to enantiopure (R)−1−trimethylsilylethanol was successfully conducted in a biphasic water−immiscible ionic liquid (IL)/buffer system using immobilized Candida parapsilosis CCTCC M203011 cells. Of all the tested ILs, the best result was observed with BMIM•PF6, which exhibited not only good biocompatibility with the cells but also excellent solvent properties for the toxic substrate and product. To better understand the bioreduction, several crucial influential variables were also examined. The optimum volume ratio of buffer to BMIM•PF6, buffer pH, reaction temperature and substrate concentration were 8/1, 6.0, 30ºC and 120mM, respectively. Under the optimized conditions, the maximum yield and the product e.e. were as high as 97.1% and >99%, respectively, which are much higher than the corresponding values with the aqueous system or the biphasic n−hexane/buffer system. Additionally, the immobilized cells displayed a better operational stability in BMIM•PF6−based biphasic system. |
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Heterocycles and Aromatics, Asymmetric Reactions and Syntheses and Total Synthesis of Complex Molecules
7:00 PM-9:00 PM, Wednesday, August 19, 2009 Walter E. Washington Convention Center -- Ballroom C, Poster
Division of Organic Chemistry |