Enantioselective Analysis of Secondary Alcohols and Their Esters in Purple and Yellow Passion Fruits
摘要:
The enantiomeric compositions of the acetates, butanoates, hexanoates, and octanoates of the secondary alcohols 2-pentanol, 2-heptanol, and 2-nonanol were determined in yellow (Passiflora edulis f. flavicarpa) and purple (Passiflora edulis Sims) passion fruits. The compounds were isolated by means of simultaneous distillation-extraction. Enantiodifferentiation was performed via multidimensional gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin as chiral stationary phase. The series of homologous 2-alkyl esters, which are typical constituents of purple passion fruits, were shown to be present as nearly optically pure (R)-enantiomers. The proportions of the (S)-enantiomers varied in different batches and were dependent on the alcohol moieties of the esters. For minor amounts of esters detected in yellow fruits, the (R)-enantiomers were also dominating. However, the enantiomeric excesses were significantly lower than in the purple variety. Enantioselective analysis of the free alcohols revealed that 2-heptanol exhibited opposite configurations in purple and yellow passion fruits. A similar phenomenon was observed for 2-pentanol, which was present in the yellow fruits as a nearly racemic mixture. Data determined in extracts obtained by other techniques (liquid-liquid extraction, vacuum headspace technique) showed that the isolation procedure had no significant impact on the enantiomeric ratios.
Enantioselective Analysis of Secondary Alcohols and Their Esters in Purple and Yellow Passion Fruits
作者:Hedwig Strohalm、Márta Dregus、Astrid Wahl、Karl-Heinz Engel
DOI:10.1021/jf072464n
日期:2007.12.1
The enantiomeric compositions of the acetates, butanoates, hexanoates, and octanoates of the secondary alcohols 2-pentanol, 2-heptanol, and 2-nonanol were determined in yellow (Passiflora edulis f. flavicarpa) and purple (Passiflora edulis Sims) passion fruits. The compounds were isolated by means of simultaneous distillation-extraction. Enantiodifferentiation was performed via multidimensional gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin as chiral stationary phase. The series of homologous 2-alkyl esters, which are typical constituents of purple passion fruits, were shown to be present as nearly optically pure (R)-enantiomers. The proportions of the (S)-enantiomers varied in different batches and were dependent on the alcohol moieties of the esters. For minor amounts of esters detected in yellow fruits, the (R)-enantiomers were also dominating. However, the enantiomeric excesses were significantly lower than in the purple variety. Enantioselective analysis of the free alcohols revealed that 2-heptanol exhibited opposite configurations in purple and yellow passion fruits. A similar phenomenon was observed for 2-pentanol, which was present in the yellow fruits as a nearly racemic mixture. Data determined in extracts obtained by other techniques (liquid-liquid extraction, vacuum headspace technique) showed that the isolation procedure had no significant impact on the enantiomeric ratios.
Preparation of Passion Fruit-Typical 2-Alkyl Ester Enantiomers via Lipase-Catalyzed Kinetic Resolution
作者:Hedwig Strohalm、Susanne Dold、Kathrin Pendzialek、Monika Weiher、Karl-Heinz Engel
DOI:10.1021/jf100432s
日期:2010.5.26
fruit-typical 2-alkyl esters by capillary gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-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
研究了通过脂肪酶催化动力学拆分制备仲醇2-戊醇,2-庚醇和2-壬醇的酯对映体(乙酸,丁酸酯,己酸酯和辛酸酯)。通过庚烷(2,3-di- O -methyl-6)的毛细管气相色谱法,对这些百香果类典型的2-烷基酯的同源系列进行了追踪,考察了市售酶制剂催化的酯化和水解反应的转化率和立体化学过程。- ø -叔丁基二)-β环糊精作为手性固定相。开发了一种通过脂肪酶催化的酯化反应制备酯对映体的有效方法:光学纯(R通过用对映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)-2-烷基酯(ee> 99.9%)。随后使用来自假丝酵母的脂肪酶将未反应的醇酯化,得到光学富集的(S)-酯(ee> 81.4%)。通过使用硅胶和氧化铝(碱性)的混合物的液体固体色谱法分离产物,得到高化学纯度和产率(> 40mol%)。