Palladium-catalyzed regioselective C-H bond arylations at the C3 position of ortho-substituted fluorobenzenes.

The influence of an ortho-substituent on fluorobenzene derivatives for palladium-catalyzed C-H bond arylation has been explored. In the presence of 2-bromo, 2-chloro and 2-methoxy substituents, the reaction proceeds nicely using a diphosphine-palladium catalyst and potassium acetate/dimethylacetamide (PivOK/DMA) as the catalytic system. In all cases, a regioselective arylation at the other ortho-position to the fluorine atom (C3) was observed. A variety of electron-withdrawing substituents on the aryl bromide coupling partner, such as formyl, nitro, nitrile, and also heteroaryl bromides, was tolerated. Moreover, tri(hetero)aryl derivatives containing a fluorobenzene as the central unit have been prepared from 2-bromofluorobenzene through palladium-catalyzed-successive C-H bond (hetero)arylations.