Despite increasing pharmaceutical importance, fluorinated aromatic organic molecules remain difficult to synthesize. Present methods require either harsh reaction conditions or highly specialized reagents, making the preparation of complex fluoroarenes challenging. Thus, the development of general methods for their preparation that overcome the limitations of those techniques currently in use is of great interest. We have prepared [LPd(II)Ar(F)] complexes, where L is a biaryl monophosphine ligand and Ar is an aryl group, and identified conditions under which reductive elimination occurs to form an Ar-F bond. On the basis of these results, we have developed a catalytic process that converts aryl bromides and aryl triflates into the corresponding fluorinated arenes by using simple fluoride salts. We expect this method to allow the introduction of fluorine atoms into advanced, highly functionalized intermediates.
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http://dx.doi.org/10.1126/science.1178239 | DOI Listing |
J Am Chem Soc
January 2025
Department of Chemistry, University of Wisconsin─Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
Aryl triflates make up a class of aryl electrophiles that are available in a single step from the corresponding phenol. Despite the known reactivity of nickel complexes for aryl C-O bond activation of phenol derivatives, nickel-catalyzed cross-electrophile coupling using aryl triflates has proven challenging. Herein, we report a method to form C(sp)-C(sp) bonds by coupling aryl triflates with alkyl bromides and chlorides using phenanthroline (phen) or pyridine-2,6-bis(-cyanocarboxamidine) (PyBCam)-ligated nickel catalysts.
View Article and Find Full Text PDFChem Commun (Camb)
December 2024
Department of Chemistry, School of Pharmacy, Air Force Medical University, Xi'an, 710032, China.
An efficient synthesis of continuously substituted quinoline derivatives palladium-catalyzed intramolecular 6- imidoylative cyclization of -alkenyl aryl isocyanides with (hetero)aryl halides or vinylic triflates has been developed. The reaction proceeds through the concerted metalation-deprotonation (CMD) mechanism by activation of a vinyl C-H bond with imidoylpalladium assisted by the carboxylate.
View Article and Find Full Text PDFOrg Lett
January 2025
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K.
Simple aryl chlorides represent challenging substrates in iron-catalyzed borylation. A combination of Li[B(Bu)pin-Bpin] as the borylating reagent and a catalyst formed in situ from iron(II) triflate and the commercially available N-heterocyclic carbene ligand, IMes, gives significantly improved activity and a much broader scope than previously reported iron-based catalysts. Iron triflate is also a good precatalyst for the borylation of aryl triflates─a previously unreported transformation─and in these cases the IMes ligand is not required.
View Article and Find Full Text PDFJ Org Chem
December 2024
Department of Chemistry, Sidho-Kanho-Birsha University, Purulia 723104, W.B., India.
Distinctive, green, innovative, and well-organized photoinduced (metal- or photocatalyst-free) regioselective decarbonylative and decarboxylative C-O bond functionalization protocols to access aryl 2-aminobenzoates and 2-substituted benzoxazinone derivatives in excellent yields have been devised. These are achieved through the chemoselective scission of isatoic anhydride with ketones, diaryliodonium triflate, nitroalkene, phthalazinone, and phenol derivatives, which, in turn, served as the representative "electrophilic and nucleophilic" coupling partners. Control experiments and DFT calculations reveal that electrophilic radical-bearing coupling partners specifically follow the decarbonylation pathway, while nucleophilic radical-bearing conjugates facilitate the decarboxylation process.
View Article and Find Full Text PDFOrg Lett
November 2024
Institute of Organic Chemistry, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany.
In this report, we describe a simple method for the synthesis of 2-aryl-2-vinyl-cyclobutanones through the reaction of in situ generated cyclopropanones and cinnamylsulfonium ylides, representing an example of a formal carbene insertion into these three-membered rings. The cyclobutanones thus obtained are ideal substrates for palladium-catalyzed coupling reactions upon enol triflate formation, thereby providing access to densely functionalized cyclobutenes. A mechanistic proposal for the ring-enlargement is presented based on experimental evidence.
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