coumarin-3-carboxylic acids is developed. This approach enables controlled protodecarboxylation/regioselective C–H arylation of coumain-3-carboxylic acids in one-pot using a monometallic catalytic system. A wide variety of electron-donating and -withdrawing substituents on both coumarins and arylboronic acid are tolerated under the reaction conditions and 4-aryl coumarins are constructed in high yields.
A straightforward and atom-economical base-free palladium-catalyzed regioselective direct arylation of coumarins and chromenones is devised. This protocol is compatible with a wide variety of electron-donating and -withdrawing substituents and allows construction of various biologically important flavone and neoflavone backbones.
Copper/Selectfluor-System-Catalyzed Dehydration-Oxidation of Tertiary Cycloalcohols: Access to β-Substituted Cyclohex-2-enones, 4-Arylcoumarins, and Biaryls
作者:Shaobo Ren、Jian Zhang、Jiahui Zhang、Heng Wang、Wei Zhang、Yunkui Liu、Miaochang Liu
DOI:10.1002/ejoc.201500610
日期:2015.8
A route to β-substitutedcyclohex-2-enones, 4-arylcoumarins, and biaryls has been developed. This approach involves a one-pot Cu0/Selectfluor-catalyzed dehydration–oxidation of tertiary cycloalcohols. Thus, by using 2 equiv. of Selectfluor at 25 °C, the dehydration–oxidation of tertiary cyclohexanols and oxabenzocyclohexanols gave β-substitutedcyclohex-2-enones and 4-arylcoumarins, respectively; whereas
Heck and oxidative boron Heck reactions employing Pd(II) supported amphiphilized polyethyleneimine‐functionalized MCM‐41 (MCM‐41@aPEI‐Pd) as an efficient and recyclable nanocatalyst
MCM‐41@PEI‐dodecane and the resulted MCM‐41@aPEI‐Pd nanocatalyst was characterized by FT‐IR, TEM, ICP‐AES and XPS. Our designed nanocatalyst with a distinguished core‐shell structure and Pd2+ ions as catalytic centers was explored as an efficient and recyclable catalyst for Heck and oxidative boron Heckcouplingreactions. In Heckcouplingreaction, the catalytic activity of MCM‐41@aPEI‐Pd in the presence of triethylamine