Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo n. 542/2, 166 10 Prague 6, Czech Republic; Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 21 Prague 8, Czech Republic.
Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo n. 542/2, 166 10 Prague 6, Czech Republic; University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic.
Bioorg Med Chem. 2019 Apr 1;27(7):1246-1253. doi: 10.1016/j.bmc.2019.02.022. Epub 2019 Feb 13.
An enzymatic alternative to the chemical synthesis of chiral gem-difluorinated alcohols has been developed. The method is highly effective and stereoselective, feasible at laboratory temperature, avoiding the use of toxic heavy metal catalysts which is an important benefit in medicinal chemistry including the synthesis of drugs and drug precursors. Candida antarctica lipases A and B were applied for the enantioselective resolution of side-chain modified gem-difluorinated alcohols, (R)- and (S)-3-benzyloxy-1,1-difluoropropan-2-ols (1a and 1b), compounds serving as chiral building blocks in the synthesis of various bioactive molecules bearing a gem-difluorinated grouping. The catalytic activity of these lipases was investigated for the chiral acetylation of 1a and 1b in non-polar solvents using vinyl acetate as an acetyl donor. The dependence of the reaction course on various substrate and enzyme concentrations, reaction time, and temperature was monitored by chiral capillary electrophoresis (CE) using sulfobutyl ether β-cyclodextrin as a stereoselective additive of the aqueous background electrolyte. The application of CE, NMR, and MS methods has proved that the complex enzyme effect of Candida antarctica lipase B leads to the thermodynamically stable (S)-enantiomer 1b instead of the expected acetylated derivatives. In contrast, the enantioselective acetylation of racemic alcohol 1 was observed as a kinetically controlled process, where (R)-enantiomer 1a was formed as the main product. This process was followed by enzymatic hydrolysis and chiral isomerisation. Finally, single pure enantiomers 1a and 1b were isolated and their absolute configurations were assigned from NMR analysis after esterification with Mosher's acids.
已开发出一种酶法替代化学方法来合成手性偕二氟代醇。该方法高效且具有立体选择性,在实验室温度下可行,避免了使用有毒重金属催化剂,这在包括药物和药物前体合成在内的药物化学中是一个重要的优势。南极假丝酵母脂肪酶 A 和 B 被应用于侧链修饰的偕二氟代醇(R)-和(S)-3-苄氧基-1,1-二氟-2-丙醇(1a 和 1b)的对映选择性拆分,这些化合物是合成各种含有偕二氟代基团的生物活性分子的手性构建块。研究了这些脂肪酶在非极性溶剂中使用醋酸乙烯酯作为乙酰供体对手性 1a 和 1b 的手性乙酰化的催化活性。通过手性毛细管电泳(CE)使用磺丁基醚-β-环糊精作为水相背景电解质的立体选择性添加剂,监测了各种底物和酶浓度、反应时间和温度对反应过程的影响。CE、NMR 和 MS 方法的应用证明了南极假丝酵母脂肪酶 B 的复杂酶作用导致热力学稳定的(S)-对映体 1b 而不是预期的乙酰化衍生物。相比之下,对映体 1 的对映选择性乙酰化被观察为动力学控制过程,其中(R)-对映体 1a 作为主要产物形成。该过程随后进行酶水解和手性异构化。最后,通过与 Mosher 酸酯化后进行 NMR 分析,分离出单一纯对映体 1a 和 1b,并确定了它们的绝对构型。