从d -(+)-甘露醇开始直接合成 (+)-反式-(4 S ,5 R )- 和 (+)-顺式-(4 R ,5 R )-威士忌内酯的报道较少与涉及d-甘露醇作为手性池起始材料的现有文献方法相比,有效步骤的数量。Chiron 方法直接将d-甘露醇的手性转化为这些靶分子中的两个手性中心之一。为此,立体异构纯的反式和顺式在倒数第二步中形成碘甲基-γ-内酯。这两种作为通用的高级通用中间体也分别转化为 (+)-反式-(4 S ,5 R )- 和 (+)-顺式-(4 R ,5 R )-干邑内酯。据我们所知,迄今为止还没有报道从d-甘露醇开始合成干邑内酯。所有这些内酯都被确定为陈年酒精饮料的关键香气成分。
Enantioselective, Catalytic One‐Pot Synthesis of
<i>γ</i>
‐Butyrolactone‐Based Fragrances
作者:Ceyda Kumru、Thomas Classen、Jörg Pietruszka
DOI:10.1002/cctc.201801040
日期:2018.11.7
Herein the preparative (1 g scale), stereoselective syntheses of various alkyl‐substituted γ‐butyrolactone fragrances 1 is described. The α,β‐unsaturated γ‐keto esters 2 as starting materials were synthesized by a Horner‐Wadsworth‐Emmons reaction and are further reduced by an ene reductase and alcohol dehydrogenase in a one‐pot enzyme cascade to nine desired γ‐butyrolactones 1, among them whisky (1 c)
Synthesis of γ-Lactones via the Kowalski Homologation Reaction: Protecting-Group-Free Divergent Total Syntheses of Eupomatilones-2,5,6, and 3-<i>epi</i>-Eupomatilone-6
作者:Hosam Choi、Hanho Jang、Hyoungsu Kim、Kiyoun Lee
DOI:10.1021/acs.orglett.9b02848
日期:2019.10.4
A highly efficient synthesis of functionalized chiral γ-butyrolactone scaffolds has been described. The basis of the approach is the Kowalski ester homologation that is modified for our proposed transformation. The newly developed methodology combines a divergent synthetic strategy to permit a straightforward protecting-group-free asymmetric totalsyntheses of eupomatilones-2,5,6, and 3-epi-eupomatilone-6
best choice for the bioreduction of ethyl 2-oxocyclohexylacetate 2e, which afforded cis-(−)-5e and trans-(−)-5e with 98 and 99% e.e., respectively. Reduction of 3-(2-oxocyclohexyl)propionic acid 3e with Pichia glucozyma gave predominantly the corresponding δ-lactone trans-(−)-6e with 94% e.e., whose absoluteconfiguration was determined by means of CD spectroscopy.
In this report, we present a highly efficient approach for the synthesis of β,γ-disubstituted γ-butyrolactone motifs. This newly developed strategy is based on the combination of a diastereoselective aldol and a nickel carbene-mediated γ-butyrolactonization and uses an effective intramolecular ring closure to rapidly access a range of functionalized chiral γ-butyrolactones. This single-step approach
Atom transfer radical cyclization (ATRC) applied to a chemoenzymatic synthesis of Quercus lactones
作者:Fulvia Felluga、Cristina Forzato、Franco Ghelfi、Patrizia Nitti、Giuliana Pitacco、Ugo Maria Pagnoni、Fabrizio Roncaglia
DOI:10.1016/j.tetasy.2007.02.012
日期:2007.3
The natural fragrances (+)-trans whisky lactone 2 and (+)-trans cognac lactone 4, together with a minor amount of their (-)cis stereoisomers, were prepared in 50% and 42% overall yield, respectively, starting from racemic 1-hepten-3-ol (+/-)-5 and 1-octen-3-ol (+/-)-6. The procedure involved first the enantioconvergent, lipase mediated transformation of the secondary allylic alcohols derived dichloroacetates (+/-)-7 and (+/-)-8 into the corresponding homochiral (+)-7 and (+)-8, combined with their cyclization under a transition metal catalyzed atom transfer process. (c) 2007 Elsevier Ltd. All rights reserved.