Palladium(II)-catalyzed arylation of arenes with aryl boronic acids and a free amine as directing group in aqueous medium has been developed. High reactivity and chemoselectivity for the formation of carbon-carbon bonds were achieved by the use of soluble silver salts. The addition of water is crucial to improve the arylation yield.
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http://dx.doi.org/10.1002/chem.201301229 | DOI Listing |
Dalton Trans
January 2025
Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
In this work, we show two synthetic routes to substitute the N position of mesoionic imines (MIIs). By Buchwald-Hartwig amination, 5-amino-1,2,3-triazoles can be arylated at the said position, showing the versatility of amino-triazoles as building blocks for MIIs. The reaction of MIIs with electrophiles (MeI, fluoro-arenes) highlights the nucleophilic nature of MIIs as even at room temperature aromatic C-F bonds can be activated with MIIs.
View Article and Find Full Text PDFJ 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 PDFOrg Lett
December 2024
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong 999077, P. R. China.
The benzoxazole core, featuring a sterically congested 2,6-disubstituted aryl fragment at the C2 position, exhibits exclusive three-dimensional structures that are essential for particular applications in material science and pharmaceutical development. Despite their importance, the synthesis of these compounds has posed challenges with an efficient preparation strategy still lacking. In this study, we introduced a new indolylphosphine ligand, , specifically designed to facilitate the C2-H arylation of benzoxazoles with sterically hindered aryl chlorides in general.
View Article and Find Full Text PDFOrg Lett
December 2024
Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
Arylborane complexes ligated by N-heterocyclic carbenes (NHCs) can be synthesized by photoirradiation of a mixture of NHC-boranes and sulfonyl(hetero)arenes. The reaction occurs under mild and convenient conditions without any photocatalyst, which are realized by a radical chain mechanism involving NHC-boryl radicals and sulfonyl radicals. This reaction offered the opportunity to reveal the photophysical property of a 2-borylnaphtho[1,2-]thiazole derivative.
View Article and Find Full Text PDFChem Asian J
November 2024
Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, China.
Since the initial report, the Friedel-Crafts reaction has become a powerful tool to functionalize arenes. Nevertheless, the use of nitrogen heterocycles as electrophiles in Friedel-Crafts reactions has been less explored. Here, we show a Friedel-Crafts-like reaction of electron-rich arenes with quinazolin-4(3H)-ones, enabling late-stage C2-H arylation of quinazolin-4(3H)-ones via triflic anhydride (TfO) activation.
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