生物催化不对称还原制备(R)-1-[3,5-二(三氟甲基)苯基]乙醇研究进展

Advances in the production of(R)-1-[3,5-bis(trifluoromethyl)phenyl]ethanol via an asymmetric and biocatalytic reduction reaction

(R)-1-[3,5-二(三氟甲基)苯基]乙醇是合成药物阿瑞匹坦的关键中间体.以羰基还原酶生物催化前手性酮3,5-二(三氟甲基)苯乙酮的方法制备该中间体具有立体选择性优异、反应条件温和、对环境友好等优点,近年来受到广泛关注,目前已报道的高立体选择性酶源(产物ee>99%)有10余种.其中原始菌株生物催化体系能够转化底物的浓度普遍低于200 mmol/L,而利用重组Escherichia coli全细胞或者粗酶液则可催化1 mol/L以上的底物.通过添加离子液体、深共熔溶剂等辅溶剂,羰基还原酶与葡萄糖脱氢酶融合表达以及酶固定化技术等方法优化反应体系可以有效提高底物转化效率.有些羰基还原酶,如LXCAR、KR01、Ch KRED20等,能够催化异丙醇脱氢实现辅酶自循环,其催化体系具有明显优势.未来利用蛋白质工程技术对野生型的潜力酶进行人工进化,可以进一步提高利于工业应用的酶学性能,同时稳定的生产工艺、规模放大、后处理等方面也需要深入开展研究.(图2表3参52)

The(R)-1-[3,5-bis(trifluoromethyl)phenyl]ethanol[(R)-1 b]is a key intermediate in the synthesis of the chiral drug Aprepitant.The asymmetric reduction of the prochiral 1-[3,5-bis(trifluoromethyl)phenyl]ethanone(1 a)by carbonyl reductases(ketoreductases)can be an efficient and powerful method for producing highly optically-active(R)-1 b,which has become popular in recent years due to its excellent stereoselectivity,mild reaction conditions,and environmental friendliness.At present,more than 10 strains and ketoreductases with excellent(R)-stereoselectivity for substrate 1 a(ee>99%)have been screened from environmental soils or gene databases.When whole cells of isolated strains were applied to reduce 1 a,the concentrations of the transformed substrates were generally lower than 200 mmol/L.However,the whole cells of recombinant Escherichia coli or cell-free enzymes could catalyze up to 1 mol/L substrate concentrations.Several methods have been used to improve the catalytic efficiency,such as adding cosolvents in terms of ionic liquids and deep eutectic solvent as well as co-expressing with glucose dehydrogenase and using immobilization technologies.Ketoreductases,such as LXCAR,KR01 and Ch KRED20,that can regenerate coenzymes NAD(P)H with isopropanol,are clearly beneficial in(R)-1 b production.Furthermore,molecule evolution of these potential enzymes using protein engineering technology could improve their performances for industrial applications.Stable processing,large-scale productions,and post-treatment still require further studies.