Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd2(dba)3, Pd(acac)2, PdCl2(cod), [PdCl(allyl)]2, PdCl2(PhCN)2, PdCl2(PPh3)2) and ionic liquids (CILs) with L-prolinate or L-lactate anions. All the tested CILs caused remarkable increases of the conversion values and in all of the reactions 2-phenyl-2,3-dihydrofuran (3) was obtained as the main product with a yield of up to 59.2%. The highest conversions of iodobenzene were achieved for the [PdCl(allyl)]2 precursor. Formation of Pd(0) nanoparticles, representing the resting state of the catalyst, was evidenced by TEM.
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http://dx.doi.org/10.3390/molecules19068402 | DOI Listing |
J Org Chem
December 2024
Universitaet Potsdam, Institut fuer Chemie, Karl-Liebknecht-Straße 24-25, D-14476 Potsdam-Golm, Germany.
The synthesis of coumarin- and flavonoid-chalcone hybrids via Pd-catalyzed Heck-type coupling of arene diazonium salts and 8-allylcoumarins and -flavonoids is reported. The β-hydride elimination step proceeds with high regioselectivity if an OMOM-substituent is present at the position C7, adjacent to the allyl group. A selective allylic oxidation of the coupling products was accomplished using DDQ in the presence of silica to furnish the chalcones.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal-, 462 066, India.
We recently reported the gold-catalyzed Heck and chain-walking reactions, which utilize migratory insertion, β-hydride elimination steps in a catalytic fashion. Budzelaar et al. in their correspondence state that these reactions proceed through gold-catalyzed alkene heteroarylation followed by acid-mediated elimination and cyclization sequence.
View Article and Find Full Text PDFOrg Lett
November 2024
pi-Conjugated Polymers Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan.
An operationally simple and robust method for the direct arylation and ring closure of benzofurans is reported. Besides the mild conditions and good reaction yields, the methodology is applicable for a wide range of derivatives using commercially available aryl iodides with complete C regioselectivity. The reaction is proposed to follow a Heck-type oxyarylation mechanism.
View Article and Find Full Text PDFThe Herrmann-Beller catalyst, Pd[(C^P)(μ-OAc)], is readily formed by reaction of the cyclic trimer of 'Pd(OAc)' with P(-tol). In the presence of hydroxide, Pd(C^P)(μ-OAc)] converts to [Pd(C^P)(μ -OH)]. Here, we report how this activated Pd precatalyst species, and related species, serve as a conduit for formation of higher order Pd clusters containing multiple cyclopalladated P(-tol) ligands.
View Article and Find Full Text PDFChem Rec
November 2024
Laboratório de Síntese Orgânica Limpa-LASOL, CCQFA, Universidade Federal de Pelotas-UFPel, P.O. Box 354, 96010-900, Pelotas, RS, Brazil.
This report outlines the evolution and recent progress about the different protocols to synthesize the N-heterocycles fused hybrids, specifically [1,2,3]triazolo[1,5-a]quinoline. This review encompasses a broad range of approaches, describing several reactions for obtaining this since, such as dehydrogenative cyclization, oxidative N-N coupling, Dieckmann condensation, intramolecular Heck, (3+2)-cycloaddition, Ullman-type coupling and direct intramolecular arylation reactions. We divided this review in three section based in the starting materials to synthesize the target [1,2,3]triazolo[1,5-a]quinolines.
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