Synthesis of Functionalized Chromene and Chroman Derivatives via Cesium Carbonate Promoted Formal [4 + 2] Annulation of 2′-Hydroxychalcones with Allenoates
作者:Hossein Rouh、Yangxue Liu、Nandakumar Katakam、Lilian Pham、Yi-Long Zhu、Guigen Li
DOI:10.1021/acs.joc.8b02627
日期:2018.12.21
A new strategy has been established for the synthesis of functionalized chromene and chroman derivatives via a Cs2CO3-catalyzed domino addition of 2′-hydroxychalcone derivatives with allenoates, which can serve as a general avenue for the construction of multireplaced chromene derivatives. Chemoselectivity of this synthesis was found to depend on substituents on substrates. Good to excellent yields
已经建立了通过Cs 2 CO 3催化的2'-羟基查耳酮衍生物与烯丙酸酯的多米诺加成来合成官能化的色烯和苯并二氢吡喃衍生物的新策略,其可以用作构建多取代的色烯衍生物的一般途径。发现该合成的化学选择性取决于底物上的取代基。在简单和温和的条件下,在室温下获得了良好的优良收率。
Controllable Synthesis of Two Isomers 4<i>H</i>-Chromene and 2,8-Dioxabicyclo[3.3.1]nonane Derivatives under Catalyst-Free Conditions
A one-pot method for the selective synthesis of twoisomers 4H-chromene and 2,8-dioxabicyclo[3.3.1]nonane derivatives was developed without a catalyst and using EtOH/H2O (4:1, v/v) as the solvent. The reaction was conducted under mild conditions, with forming multiple chemical bonds in one pot and high atom economy, and only a stoichiometric amount of H2O is produced as the byproduct. Its selectivity
开发了一种选择性合成两种异构体 4 H -色烯和 2,8-二氧杂双环 [3.3.1] 壬烷衍生物的一锅法,无需催化剂,使用 EtOH/H 2 O (4:1, v/v)作为溶剂。该反应在温和的条件下进行,一锅形成多个化学键,原子经济性高,副产物仅产生化学计量的H 2 O。其选择性受热力学和动力学控制,并讨论了两种结构发生转变的原因。
A bio-inspired synthesis of hybrid flavonoids from 2-hydroxychalcone driven by visible light
deliver structurally diverse hybrid flavonoids in good to excellent yields in the presence of a catalytic Brønsted acid. Moreover, moderate enantioselectivities could be obtained using a catalytic chiral phosphoric acid via counter anion directed addition. Based on mechanistic studies, the reaction is proposed to proceed via tandem double-bond isomerization/dehydratedcyclization of 2-hydroxychalcone
描述了一种由 2-羟基查耳酮合成的杂合类黄酮的仿生合成。在 24 W CFL 的照射下,2-羟基查耳酮与各种亲核试剂反应,在催化布朗斯台德酸存在下以良好至优异的产率提供结构多样的杂化黄酮类化合物。此外,使用催化手性磷酸通过反阴离子定向加成可以获得中等的对映选择性。基于机理研究,该反应被提议通过2-羟基查耳酮的串联双键异构化/脱水环化形成瞬时黄鎓阳离子,该阳离子被亲核试剂原位捕获以提供杂化黄酮类化合物。
A combination of polarity reversal, Diels–Alder cycloaddition and skeletal remodeling to access pyridine-fused nitrones
作者:Huabin Han、Chaoyang Li、Xinyue Niu、Yuxia Wang、Wenjing Zhang、Qilin Wang
DOI:10.1039/d2cc00155a
日期:——
An unprecedented cascade strategy consisting of polarity reversal, normal electron-demand Diels–Alder cycloaddition and skeletal remodeling was developed to construct novel pyridine-fused nitrones in up to 82% yield. The key to the success was the umpolung process, which transformed the electron-deficient 3-nitropyridinium ring into a reactive, π-extended cyclic nitroalkene, serving as a rarely reported
Tandem <i>phospha</i>-Michael addition/cyclization/dehydration of 2-hydroxychalcones with <i>H</i>-phosphine oxides for the synthesis of 4-phosphorylated 4<i>H</i>-chromenes
tandem phospha-Michael addition/cyclization/dehydration of 2-hydroxychalcones with H-phosphine oxides is presented. This protocol provides a new and supplementary approach for the preparation of 4-phosphorylated 4H-chromenes in good yields (up to 99%). In addition, this domino reaction allows the successful construction of two new C–P and C–O bonds in a one-pot operation.