Synthesis of Flavonols via Pyrrolidine Catalysis: Origins of the Selectivity for Flavonol versus Aurone
作者:Wei Xiong、Xiaohong Wang、Xianyan Shen、Cuifang Hu、Xin Wang、Fei Wang、Guolin Zhang、Chun Wang
DOI:10.1021/acs.joc.0c01869
日期:2020.10.16
method for flavonol from 2′-hydroxyl acetophenone and benzaldehyde promoted by pyrrolidine under an aerobic condition in water is established. This protocol was supported by efficient synthesis of 44 common examples and three natural products. The α, β-unsaturated iminium ion (enimine ion E) was proved to be the key intermediate in the reaction. H218O and 18O2 isotope tracking experiments demonstrated
建立了一种在水中好氧条件下由吡咯烷促进的2'-羟基苯乙酮和苯甲醛合成黄酮醇的新方法。该协议得到44个常见实例和三种天然产物的有效合成的支持。事实证明,α,β-不饱和亚胺离子(亚胺离子E)是反应的关键中间体。H 2 18 O和18 O 2同位素跟踪实验表明,水和好氧气氛对于确保转化都必不可少。黄酮醇或金酮的选择性源自溶剂触发的中间体,该中间体由分离的亚胺的紫外可见光谱确定。酚亚胺EA在水中占主导地位,酮烯胺中间体EB在乙腈中盛行。在环化和[2 + 2]氧化的关键步骤之后,在吡咯烷和氧的存在下,EA通过EI(两性离子样的酚氧基亚胺离子)通过EI生成黄酮醇。EB通过路径II进行,这是由EB与吡咯烷和氧气共同光解而引发的自由基过程,从而生成金酮。初步的机械研究报道。
Synthesis of 5-subsituted flavonols via the Algar-Flynn-Oyamada (AFO) reaction: The mechanistic implication
作者:Xianyan Shen、Qiang Zhou、Wei Xiong、Wenchen Pu、Wei Zhang、Guolin Zhang、Chun Wang
DOI:10.1016/j.tet.2017.06.064
日期:2017.8
Herein, we report a synthetic method with improved selectivity for 5-substituted flavonols via the Algar-Flynn-Oyamada reaction (AFO), by using of sodium carbonate/hydrogen peroxide A series of 5-substituted flavonols was obtained with moderate to high yields. The mechanism of the AFO reaction was elucidated. LCMS analysis and in situ 1H NMR analysis indicated that the epoxide was involved in the transformation
本文中,我们报告了一种合成方法,该方法通过使用碳酸钠/过氧化氢,通过Algar-Flynn-Oyamada反应(AFO)对5-取代的黄酮醇进行了改进,具有中等至高收率的一系列5-取代的黄酮醇。阐明了AFO反应的机理。LCMS分析和原位1 H NMR分析表明,在碱性碱/过氧化物条件下,环氧化物参与了从查尔酮到黄酮醇和/或金酮的转化。
Chalcone dihalides—V
作者:J.A. Donnelly
DOI:10.1016/0040-4020(73)80177-2
日期:1973.1
It is shown that the action of acetic acid on 2′-acetoxy-4,6′-dimethoxychalcone dibromide results in deacetylation, debromination of the side-chain, and nuclear halogenation rather than in elimination of hydrogen bromide to form an α-bromochalcone. The generality of the dehalogenation of the α,β-dibromo ketone in acetic acid and its relation to the ortho steric effect are discussed.
Co(salpr) catalyzes the conversion of 2′-hydroxychalcones to flavanones in methanol under oxygen. Base catalysis by Co(salpr) (OH) produced in situ is responsible for the reaction, which is found to proceed reversibly.