Isolation of racemic 2,4-pentanediol and 2,5-hexanediol from commercial mixtures of racemic and meso isomers by way of cyclic sulfites.
作者:Gaétan Caron、Romas J. Kazlauskas
DOI:10.1016/0957-4166(94)80028-6
日期:1994.4
selectively reacted with SOCl2 to give a cyclic sulfite that was removed by column chromatography to leave (±)-2,92% de, 1.4 g, 55% yield. For 3, both meso and racemic isomers reacted with SOCl2 to give cyclic sulfites, but the sulfite derived from the meso isomer rearranged to trans-2,5-dimethyltetrahydrofuran under acidic conditions. Hydrolysis of the remaining sulfite gave (±)-3,84% de, 1.1 g, 37% yield
使用C对映体纯的二醇2对称如23丁二醇,1,2,4-戊二醇,2,和2,5-己二醇,3,是有用的手性助剂,但它们是昂贵的,因为化学家缺乏良好的合成途径同时消除内消旋异构体和一种对映异构体。酶解有效分离了对映异构体,但没有去除内消旋异构体。为了简化2和3的酶拆分,我们开发了简单的方法从外消旋和内消旋异构体的商业混合物中分离外消旋异构体。对于2,内消旋异构体与SOCl 2选择性反应以得到环状亚硫酸酯,通过柱色谱法除去,剩下(±) - 2,92%德,1.4克,55%产率。对于3,内消旋和外消旋异构体均与SOCl 2反应生成环状亚硫酸盐,但在酸性条件下,由内消旋异构体衍生的亚硫酸盐重新排列为反式-2,5-二甲基四氢呋喃。剩余亚硫酸盐的水解得到(±)-3.84%de,1.1g,37%收率。使用洋葱假单胞菌中的脂肪酶拆分(±)-2和(±)-3,得到(2R,4R)-2-二乙酸酯,78%ee,> 97%的理论值的40%和(2R,5R)-3