Experimental and Computation Studies on<i>Candida antarctica</i>Lipase B-Catalyzed Enantioselective Alcoholysis of 4-Bromomethyl-β-lactone Leading to Enantiopure 4-Bromo-3-hydroxybutanoate
作者:Jung Yun Lim、Nan Young Jeon、A-Reum Park、Bora Min、Bum Tae Kim、Seongsoon Park、Hyuk Lee
DOI:10.1002/adsc.201200901
日期:2013.6.17
including statins, were synthesized from rac‐4‐bromomethyl‐β‐lactone through kinetic resolution. Candida antarctica lipase B (CAL‐B) enantioselectively catalyzes the ring opening of the β‐lactone with ethanol to yield ethyl (R)‐4‐bromo‐3‐hydroxybutanoate with high enantioselectivity (E>200). The unreacted (S)‐4‐bromomethyl‐β‐lactone was converted to ethyl (S)‐4‐bromo‐3‐hydroxybutanoate (>99% ee), which can
光学纯的4-溴-3-羟基丁酸酯的两个对映异构体,是他汀类各种生物活性化合物合成中的重要手性结构单元,是通过动力学拆分从rac -4-溴甲基-β-内酯合成的。南极假丝酵母脂肪酶B(CAL-B)用乙醇对映体催化β-内酯的开环,生成对映选择性高(E > 200)的(R)-4-溴3-3-羟基丁酸乙酯。未反应的(S)-4-溴甲基-β-内酯转化为(S)-4-溴-3-羟基丁酸乙酯(> 99%ee),可以进一步转化为乙基(R)-4-氰基-3-羟基丁酸酯,通过乙醇中酸催化的开环反应 分子建模表明,快速反应对映异构体(R)-溴甲基-β-内酯的立体中心距离正在反应的羰基碳约2Å。此外,反应缓慢的对映体(S)-4-溴甲基-β-内酯在溴取代基和Leu278残基的侧链之间遇到空间位阻,而反应快速的对映体没有任何空间冲突。