酵母细胞催化(S)-6-氯-5-羟基-3-羰基己酸叔丁酯的不对称还原

Asymmetric Reduction of Tert-butyl (S)6-chloro-5-hydroxy-3-oxo-hexanoate Catalyzed by Yeast Cells

通过实验筛选出了对(S)-6-氯-5-羟基-3-羰基己酸叔丁酯具有较强还原能力的菌株。利用热预处理的方法提高了反应的立体选择性,并以稳定期的菌株为催化剂,考察菌龄、底物的加入量、菌体浓度、转化时间、转化温度和pH值对该反应的影响,得到较佳的反应条件是30℃,pH值6.0,底物浓度1 g/L,湿菌体浓度100 g/L,转化48 h。在此条件下进行反应,产物的收率和d.e.值可分别达到68.3%和95.1%。

Some experiments to screen yeasts for reducing tert-butyl（S）-6-chloro-5-hydroxy-3-oxo- hexanoate had been carried out. It was found that yeast Rhodotorula gracilis AS 2.499 in stable stage with thermal pretreatment had the best reduction effectivity and stereoselectivity. The effects of sub- strate concentration, yeast concentration, reaction time, reaction temperature and pH on the yield and d.e. （diastereometric excess value） of asymmetric reduction product were investigated. Optimal reaction conditions were 30℃, pH 6.0, substrate concentration 1 g/L, yeast concentration 100 g/L and reaction time 48 h. Under these conditions, yield and d. e. of tert-butyl（3R, 5S）-6-cholro-3,5-di- hydroxy-hexanoate were 68.3% and 95.1% respectively.