Tandem addition/cyclization for synthesis of 2-aroyl benzofurans and 2-aroyl indoles by carbopalladation of nitriles

The first example of the palladium-catalyzed tandem addition/cyclization of 2-(2-acylphenoxy)acetonitriles with arylboronic acids has been developed, providing a new strategy for the synthesis of 2-aroyl benzofurans with excellent chemoselectivity and wide functional group compatibility. Preliminary mechanistic experiments indicate that this tandem process involves sequential nucleophilic addition generating 2-(2-acylphenoxy)-1-phenylethan-1-one followed by an intramolecular cyclization. This methodology has also been applied to the synthesis of 2-aroyl indoles and the potent CYP19 inhibitor 1-(benzofuran-2-yl(phenyl)methyl)-1H-1,2,4-triazole.