Lehrstuhl für Allgemeine Lebensmitteltechnologie, Technische Universität München, Maximus-von-Imhof-Forum 2, D-85350 Freising-Weihenstephan, Germany.
J Agric Food Chem. 2010 May 26;58(10):6328-33. doi: 10.1021/jf100432s.
The preparation of ester enantiomers (acetates, butanoates, hexanoates and octanoates) of the secondary alcohols 2-pentanol, 2-heptanol and 2-nonanol via lipase-catalyzed kinetic resolutions was investigated. Conversion rates and stereochemical courses of esterification and hydrolysis reactions catalyzed by commercially available enzyme preparations were followed for the homologous series of these passion fruit-typical 2-alkyl esters by capillary gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin as chiral stationary phase. An efficient method was developed to prepare the ester enantiomers via lipase-catalyzed esterifications: optically pure (R)-2-alkyl esters (ee > 99.9%) were obtained by esterification of the racemic alcohols with enantioselective Candida antarctica lipase B (immobilized) as catalyst. The subsequent esterification of the unreacted alcohols using lipase from Candida cylindracea yielded the optically enriched (S)-esters (ee > 81.4%). The separation of the products via liquid solid chromatography using a mixture of silica gel and aluminum oxide (basic) resulted in high chemical purities and yields (> 40 mol %).
通过脂肪酶催化的动力学拆分，研究了仲醇 2-戊醇、2-庚醇和 2-壬醇的酯对映异构体（醋酸酯、丁酸酯、己酸酯和辛酸酯）的制备。通过毛细管气相色谱法，使用七（2,3-二-O-甲基-6-O-叔丁基二甲基硅基）-β-环糊精作为手性固定相，跟踪了这些百香果典型的 2-烷基酯的同系物中由商业可得的酶制剂催化的酯化和水解反应的转化率和立体化学过程。开发了一种通过脂肪酶催化酯化制备酯对映异构体的有效方法：通过手性选择性南极假丝酵母脂肪酶 B（固定化）作为催化剂，将外消旋醇酯化，可得到光学纯（R）-2-烷基酯（ee > 99.9%）。然后，使用来自 Candida cylindracea 的脂肪酶对未反应的醇进行酯化，得到光学富集的（S）-酯（ee > 81.4%）。通过硅胶和氧化铝（碱性）混合物的固液色谱法分离产物，得到高化学纯度和产率（> 40 mol%）。
