A Systematic Study on the Bakers’ Yeast Reduction of 2-Oxoalkyl Benzoates and 1-Chloro-2-alkanones
作者:Takashi Sakai、Kou Wada、Takahiko Murakami、Kiichiro Kohra、Norihisa Imajo、Yukihiro Ooga、Sadao Tsuboi、Akira Takeda、Masanori Utaka
DOI:10.1246/bcsj.65.631
日期:1992.3
The bakers’ yeast reduction of a series of 2-oxoalkyl arenecarboxylates [R(C=O)CH2O(C=O)C6H4-p-X] (1a–f) (R = CH3 to n-C6H13; X = H) and the phenyl-modified derivatives (1g–l) (R = n-C5H11, X = OH, CH3, F, Cl, Br, or I) as well as 1-chloro-2-alkanones R(C=O)CH2Cl (6a–f) (R = CH3 to n-C6H13) were systematically investigated. The substrate specificities, configuration and %ee of the reduction products were found to be highly dependent on the length of the alkyl group (R) and the α substituent. Thus, the benzoates 1a–f gave optically active 2-hydroxyalkyl benzoates (2a–f) (R, configuration, %ee) (a: CH3, S, 99; b: C2H5, S, 98; c: C3H7, S, 26; d: n-C4H9, R, 55; e: n-C5H11, S, 15; f: n-C6H13, S, 63) in 11–91% yields. Among the modification experiments of the phenyl group, 1g–l, the p-iodo substituent markedly increased the ee from 15 to 71%, although the yield was rather lowered (22% yield). The reduction of α-chloro ketones 6a–f also gave optically active 1-chloro-2-alkanols (7a–f) [(R, configuration, %ee) (a: CH3, S, 83; b: C2H5, S, 54; c: C3H7, R, 49; d: n-C4H9, R, 80; e, n-C5H11, R, 65; f, n-C6H13, R, 41)] in 16–69% yields.
对一系列2-氧代烷基苯甲酸酯[R(C=O)CH2O(C=O)C6H4-p-X](1a-f)(R = CH3 至 n-C6H13;X = H)和苯基修饰衍生物(1g-l)(R = n-C5H11,X = OH、CH3、F、Cl、Br 或 I)以及1-氯-2-烷酮R(C=O)CH2Cl(6a-f)(R = CH3 至 n-C6H13)的面包酵母还原进行了系统研究。发现底物特异性、构型和还原产物的%ee高度依赖于烷基链的长度(R)和α取代基。因此,苯甲酸酯1a-f得到了光学活性的2-羟基烷基苯甲酸酯(2a-f)(R,构型,%ee)(a:CH3,S,99;b:C2H5,S,98;c:C3H7,S,26;d:n-C4H9,R,55;e:n-C5H11,S,15;f:n-C6H13,S,63),产率为11-91%。在苯基修饰实验中,1g-l,碘取代基显著提高了ee值,从15%增加到71%,尽管产率明显下降(产率22%)。α-氯代酮6a-f的还原也得到了光学活性的1-氯-2-烷醇(7a-f)[(R,构型,%ee)(a:CH3,S,83;b:C2H5,S,54;c:C3H7,R,49;d:n-C4H9,R,80;e,n-C5H11,R,65;f,n-C6H13,R,41)],产率为16-69%。