Transition-metal-free acid-promoted biaryl construction was achieved via intermolecular C-F/C-H cross-coupling. By treating 2-fluorobenzofurans with arenes in the presence of AlCl3, 2-arylbenzofurans were obtained. This protocol was successfully applied to the… Click to show full abstract
Transition-metal-free acid-promoted biaryl construction was achieved via intermolecular C-F/C-H cross-coupling. By treating 2-fluorobenzofurans with arenes in the presence of AlCl3, 2-arylbenzofurans were obtained. This protocol was successfully applied to the short-step orthogonal synthesis of a bioactive 2-arylbenzofuran natural product, which allows independent transformations of C-F and C-Br bonds. Mechanistic studies indicated that α-fluorine-stabilized carbocations, generated via the protonation of 2-fluorobenzofurans, served as key intermediates. The Friedel-Crafts-type C-C bond formation between the α-fluorocarbocations and arenes, followed by hydrogen fluoride elimination, afforded 2-arylbenzofurans.
               
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