Chiral 2-Aryl-2-methyl-2<i>H</i>-1-benzopyrans: Synthesis, characterization of enantiomers, and barriers to thermal racemization
作者:Guenäelle Harié、André Samat、Robert Guglielmetti、Inge van Parys、Wim Saeyens、Denis de Keukeleire、Klaus Lorenz、Albrecht Mannschreck
DOI:10.1002/hlca.19970800409
日期:1997.6.30
The ease of thermal breaking of the C(sp3)O bond of the 2-aryl-2-methyl-2H-1-benzopyrans 1–9 was evaluated by measuring the free energy (ΔG) of the racemization reaction of opticallyactive compounds. The variation of ΔG of the thermal ringopening in terms of structural modifications is discussed. The synthesis of the studied compounds, the preparative separation of enantiomers by liquid chromatography
Pd-Catalyzed Formal [3 + 3] Heteroannulation of Allylic <i>gem</i>-Diacetates: Synthesis of Chromene-Based Natural Products and Exploration of Photochromic Properties
作者:Prashant Kumar、Pravesh Kumar、Sugumar Venkataramani、S. S. V. Ramasastry
DOI:10.1021/acscatal.1c05450
日期:2022.1.21
meta-substituted phenols) to produce novel polycyclic chromenes possessing spiro-, tri-, and tetrasubstituted carbon centers. The versatility of the method is demonstrated in the synthesis of several chromene-based bioactive natural products. Further, interesting photochromic properties of the new classes of benzo[f]chromenes are also discovered.
很少探索钯催化的烯丙基偕二乙酸酯的烯丙基烷基化反应。这项工作揭示了烯丙基宝石-二乙酸酯的一种不寻常的化学反应模式,并将它们确立为合成复杂苯并[ f ]色烯系统的新原型。在反应条件下,二乙酸酯表现为 1,3-双阳离子等价物,并与 2-萘酚(和间位取代的酚)发生 [3 + 3] 杂环化反应,生成具有螺、三和四取代碳的新型多环色烯中心。该方法的多功能性在几种基于色烯的生物活性天然产物的合成中得到证明。此外,新类别苯并[ f]铬烯也被发现。
Ligand-controlled regiodivergent π-allyl palladium catalysis enables a switch between [3+2] and [3+3] cycloadditions
Catalysis by β-Cyclodextrin Hydrate - Synthesis of 2,2-Disubstituted 2<i>H</i>
-Chromenes in Aqueous Medium
作者:Avishek Ghatak、Sagar Khan、Sanjay Bhar
DOI:10.1002/adsc.201500358
日期:2016.2.4
well as propargyl ethers with differently substituted phenols under ambient atmosphere in aqueous medium has been developed using β‐cyclodextrin hydrate as an efficient, recyclable and stable catalyst. This is the first report where β‐cyclodextrin hydrate acted as a catalyst for an organic transformation but β‐cyclodextrin alone failed.