Formal Synthesis of (−)-Englerin A and Cytotoxicity Studies of Truncated Englerins
作者:Jing Xu、Eduardo J. E. Caro-Diaz、Ayse Batova、Steven D. E. Sullivan、Emmanuel A. Theodorakis
DOI:10.1002/asia.201101021
日期:2012.5
An efficient formal synthesis of (−)‐englerin A (1) is reported. The target molecule is a recently isolated guaiane sesquiterpene that possesses highly potent and selective activity against renal cancer cell‐lines. Our enantioselective strategy involved the construction of the BC ring system of compound 1 through a RhII‐catalyzed [4+3] cycloaddition reaction followed by subsequent attachment of the
报道了 (-)-englerin A ( 1 )的有效形式合成。目标分子是最近分离的愈创木酚倍半萜烯,它对肾癌细胞系具有高效和选择性的活性。我们的对映选择性策略涉及通过 Rh II构建化合物1的 BC 环系统-催化的 [4+3] 环加成反应,随后通过分子内醛醇缩合反应连接 A 环。因此,该策略允许合成截断的 englerins。用 A498 肾癌细胞系对这些类似物进行评估表明,englerin 的 A 环对其抗增殖活性至关重要。此外,对这些类似物的评估导致鉴定了 CEM 细胞的强效生长抑制剂,其 GI 50值在 1-3 μM范围内。
A solvent-free catalytic protocol for the Achmatowicz rearrangement
作者:Guodong Zhao、Rongbiao Tong
DOI:10.1039/c8gc03030h
日期:——
Reported here is the development of an environmentally friendly catalytic (KBr/oxone) and solvent-free protocol for the Achmatowiczrearrangement (AchR). Different from all previous methods is that the use of chromatographic alumina (Al2O3) allows AchR to proceed smoothly in the absence of any organic solvent and therefore considerably facilitates the subsequent workup and purification with minimal
这里报道的是针对Achmatowicz重排(AchR)的环保型催化(KBr / oxone)和无溶剂方案的开发。与所有以前的方法不同的是,使用色谱氧化铝(Al 2 O 3)可使AchR在不存在任何有机溶剂的情况下顺利进行,因此可极大地促进后续的后处理和纯化,并且对环境的影响最小。重要的是,该协议允许按比例放大(从毫克到克),回收Al 2 O 3以及与其他反应按一锅顺序方式进行整合。
Catalyst-free synthesis of biodiesel precursors from biomass-based furfuryl alcohols in the presence of H<sub>2</sub>O and air
Achmatowiczrearrangement (AchR) is a very important transformation for the synthesis of various heterocyclic building blocks and natural products. Here, the discovery of Fenton chemistry for AchR using a bifunctional catalyst (FeBr2 or CeBr3), which has environmental friendliness and a broad substrate scope at the same time has been reported. This method addresses the major limitation of conventional
Achmatowicz重排(AchR)是合成各种杂环结构单元和天然产物的非常重要的转变。在此,已经报道了使用具有环境友好性并且同时具有广泛的底物范围的双功能催化剂(FeBr 2或CeBr 3)对AchR的芬顿化学的发现。该方法解决了常规化学(危险)和酶促(有限范围)方法的主要局限性。机理研究表明,反应性溴化物种(RBS)是AchR的真正催化剂,Fenton化学[Fe / Ce(cat。)+ H 2 O 2 →HO • / HOO • + H 2O]负责将溴化物氧化为RBS。重要的是,这种在中性条件下由M-Br x -H 2 O 2生成的原位RBS解决了许多卤代过氧化物酶模拟物的长期存在的问题,这些模拟物需要强酸性添加剂/介质来与H 2 O 2进行溴化物氧化,这创造了机会用于许多其他溴介导的有机反应。