Synthesis, enzymic resolution and enantiomeric enhancement of bis(hydroxymethyl)[7]thiaheterohelicenes
Synthesis, enzymic resolution and enantiomeric enhancement of bis(hydroxymethyl)[7]thiaheterohelicenes
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双(羟甲基)[7]硫杂螺旋烯的合成、酶法拆分和对映体增强
DOI：
10.1039/a707196e
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Yoshinori Kitahara
中科院分区：
文献类型：
--
作者：
Kazuhiko Tanaka;Hideji Osuga;Hitomi Suzuki;Yuka Shogase;Yoshinori Kitahara
以2-(hydroxymethyl)benzo[1，2-b:4，3-b′]dithiophene 1为原料，经8步反应制得外消旋双(羟甲基)[7]硫杂螺烯9。洋葱假单胞菌脂肪酶催化乙酸乙烯酯在二氯甲烷中与二醇9进行酯交换反应，生成光学稳定的(P)-双(羟甲基)[7]硫杂螺烯[(P)-9]，ee为98%，同时生成相应的单乙酸酯[(M)-10]和二乙酸酯[(M)-11]。AQ对乙酸酯(M)-10和(M)-11的水解。氢氧化钠分别在77%和94%的ee中生成(M)-9。相反，用南极洲假丝酵母酶解二醇9得到了二醇(M)-9，得率为92%ee。光学富集型螺二醇9在硅胶上的柱层析显示对映体增强。讨论了这一现象的可能原因。
Racemic bis(hydroxymethyl)[7]thiaheterohelicene 9 has been prepared in eight steps (33% overall yield) from 2-(hydroxymethyl)benzo[1,2-b:4,3-b′]dithiophene 1. Lipase (Pseudomonas cepacia)-catalyzed transesterification of diol 9 by vinyl acetate in dichloromethane produces optically stable (P)-bis(hydroxymethyl)[7]thiaheterohelicene [(P)-9] with 98% ee along with the corresponding monoacetate [(M)-10] and the diacetate [(M)-11]. Hydrolysis of acetates (M)-10 and (M)-11 by aq. NaOH gives (M)-9 in 77% and 94% ee, respectively. In contrast, the enzymic resolution of diol 9 with Candida antarctica afforded diol (M)-9 in 92% ee. Column chromatography of optically enriched helicenediol 9 on silica gel shows an enantiomeric enhancement. A possible cause of the phenomenon is discussed.