Visible-Light-Induced C(sp<sup>2</sup>)–C(sp<sup>3</sup>) Coupling Reaction for the Regioselective Synthesis of 3-Functionalized Coumarins
作者:Ke Zhang、Li Qiao、Jianwei Xie、Zhenwei Lin、Hanjie Li、Ping Lu、Yanguang Wang
DOI:10.1021/acs.joc.1c00848
日期:2021.7.16
A photocatalysis strategy for the regioselective synthesis of 3-functionalized coumarins is reported. With visible light irradiation, a direct and regioselective C(sp2)–C(sp3) coupling reaction of 3-(2-hydroxyphenyl)acrylates with ethers or thioethers occurs by using Ru(bpy)3Cl2·6H2O as a photocatalyst and TBHP as an oxidant. The cascade process involves alkenylation of the C(sp3)–H bond of ethers
Palladium(<scp>ii</scp>) oxide impregnated on magnetite as a catalyst for the synthesis of 4-arylcoumarins via a Heck-arylation/cyclization process
作者:Juana M. Pérez、Rafael Cano、Gerard P. McGlacken、Diego J. Ramón
DOI:10.1039/c6ra01731b
日期:——
heterogeneous palladium(II) oxide impregnated on magnetite catalyst (2.5 mol%) with a lower catalyst loading than that reported for similar processes. Ethanol was used as a non-toxic and bio-renewable solvent. Good yields were afforded using a broad range of substrates (40–98%). The catalyst could be partially recycled, and analyses confirmed the almost total reduction of palladium(II) oxide to palladium(0) as
Rh-Catalyzed Deformylative Coupling of Salicylaldehydes with Acrylates and Acrylamides
作者:Maddali L. N. Rao、Boddu S. Ramakrishna
DOI:10.1021/acs.joc.9b00602
日期:2019.5.3
An unprecedented deformylative coupling of salicylaldehydes to acrylates and acrylamides under Rh-catalyzed conditions is reported. These deformylative couplings afforded o-hydroxycinnamates and o-hydroxycinnamamides with broad functional group tolerance and high chemoselectivity under milder reaction conditions.
Phosphine-Catalyzed Synthesis of Highly Functionalized Coumarins
作者:Christopher E. Henry、Ohyun Kwon
DOI:10.1021/ol071181d
日期:2007.8.1
[GRAPHICS]2-Styrenyl allenoates are converted into cyclopentene-fused dihydrocoumarins through phosphine-catalyzed regio- and diastereoselective [3 + 2] cycloadditions. Remarkably, changing the solvent from THF to benzene promotes the conversion of the 2-(2-nitrostyrenyl) allenoate into a tricyclic nitronate through a previously undocumented mode of phosphine catalysis. This nitronate was subjected to efficient face-, regio-, and exo-selective 1,3-dipolar cycloadditions to provide tetracyclic coumarin derivatives.
Rhodium-Catalyzed Domino Conjugate Addition−Cyclization Reactions for the Synthesis of a Variety of <i>N</i>- and <i>O</i>-Heterocycles: Arylboroxines as Effective Carbon Nucleophiles
作者:Ja Ock Park、So Won Youn
DOI:10.1021/ol100610v
日期:2010.5.21
Facile and efficient Rh(I)-catalyzed domino conjugate addition-cyclization reactions of olefins bearing two electrophilic sites and a pendant nucleophile with organoboroxines have been developed to afford a variety of N- and O-heterocycles, such as 3,4-dihydroquinolin-2(1H)-ones, 3,4-dihydrocoumarins, and pyrrolidin-2-ones, which constitute important motifs in biologically active natural and synthetic organic compounds.