transformation of enones was investigated with cultured cells of Synechococcus sp. PCC 7942 (a cyanobacterium). The cells reduced both the endocyclic C-C double bond of s-trans enones and the exocyclic C-C double bond of s-cis enones with high enantioselectivity to afford optically active α-substituted (S)-ketones under illumination. In addition, the reduction of the double bond of these enones was accompanied
用聚球藻的培养细胞研究了烯酮的不对称转化。PCC 7942(一种蓝细菌)。细胞以高对映选择性减少了 s-trans enones 的内环 CC 双键和 s-cis enones 的外环 CC 双键,以在光照下提供光学活性的 α-取代 (S)-酮。此外,这些烯酮双键的还原伴随着饱和醇的形成。细胞优先将简单的脂肪酮而不是环状酮还原为相应的(S)-醇,具有出色的对映选择性。
Effects of Lithium Salts on the Enantioselectivity of Protonation of Enolates with Chiral Imide
An increase in enantioselectivity was observed in the asymmetric protonation of prochiral enolates with a chiral imide using lithium salt as an additive. For example, (R)-enriched 2-n-pentylcyclopentanone 6 was obtained in high yield with 90% ee when the silyl enol ether 4 was treated with n-BuLi in the presence of 5 equiv of LiBr in Et2O and the resulting lithium enolate 5 was then protonated by a solution of (S,S)-imide 1 in THF. In contrast, the product 6 obtained without LiBr exhibited a lower enantiomeric excess (74% ee)
Assessing the Substrate Selectivities and Enantioselectivities of Eight Novel Baeyer−Villiger Monooxygenases toward Alkyl-Substituted Cyclohexanones
作者:Brian G. Kyte、Pierre Rouvière、Qiong Cheng、Jon D. Stewart
DOI:10.1021/jo030253l
日期:2004.1.1
4-alkyl-substituted cyclohexanones tested, enzymes were discovered that afforded each of the corresponding (S)-lactones in ≥98% ee. This was also true for the 2-alkyl-substituted cyclohexanones examined. The situation was more complex for 3-akyl-substituted cyclohexanones. In a few cases, single Baeyer−Villiger monooxygenases possessed both high regio- and enantioselectivities toward these compounds
A Novel Reductase Participating in the Hydrogenation of an Exocyclic C–C Double Bond of Enones from<i>Nicotiana tabacum</i>
作者:Kei Shimoda、Shunsuke Izumi、Toshifumi Hirata
DOI:10.1246/bcsj.75.813
日期:2002.4
A novel 74 kDa enone reductase which catalyzes the reduction of the exocyclic C–C double bond of enones was isolated from cultured cells of Nicotiana tabacum. The reductase was found to catalyze the enantiofacially selective reduction of the C–C double bond of 2-alkylidenecyclohexanone to give optically active (S)-2-alkylcyclohexanone.
Laboratory Evolution of Robust and Enantioselective Baeyer−Villiger Monooxygenases for Asymmetric Catalysis
作者:Manfred T. Reetz、Sheng Wu
DOI:10.1021/ja906212k
日期:2009.10.28
and induced fit docking suggests potential randomization sites, different from all previous approaches to focused library generation. Sites harboring highly conserved proline in a loop of the WT are targeted. The most active and enantioselective mutants retain the high thermostability of the parent WT PAMO. The success of the "proline" hypothesis in the present system calls for further testing in future