ORGN 658 |
| Efficient asymmetric reduction of acetyltrimethylsilane, catalyzed with immobilized Saccharomyces cerevisiae cells, was successfully conducted in a biphasic system containing the ionic liquid BMIM·PF6. An obvious enhancement in the initial rate and enantioselectivity of the reduction was observed by using an aqueous-BMIM·PF6 biphasic system instead of an aqueous-n-hexane biphasic system. Under the optimized conditions (with the volume ratio of buffer to BMIM·PF6 or n-hexane, buffer pH, reaction temperature and substrate concentration being 6/1, 7.3, 30ºC and 84mM for BMIM·PF6 containing system, and 1/2, 8.0, 30 ºC and 42mM for n-hexane containing system, respectively), the initial rate, the maximum yield and the product e.e. , respectively, were 63.4mM/h, 99.9% and above 99.9% for the reduction taking place in aqueous-BMIM·PF6 biphasic system, while in aqueous-n-hexane biphasic system, the corresponding values were found to be 1.45mM/h, 97.4% and 95.4%. Additionally, immobilized cells showed higher operational stability in BMIM·PF6 containing system. |
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Asymmetric Reactions, Heterocycles, Aromatics, Combinatorial, and Physical Organic Chemistry
8:00 PM-10:00 PM, Wednesday, 31 August 2005 Washington DC Convention Center -- Hall A, Poster
Division of Organic Chemistry |