Heteroaryl‐Substituted Polyfluorobiaryls Synthesis via Palladium‐Catalyzed Double CH Bond Functionalization Using Palladium 1,4‐Migration Associated to Direct Arylation

The functionalization of specific CH bonds of arenes is a topic currently receiving significant attention, as it may enable the preparation of complex molecules in fewer steps. We found that using 2‐bromo‐1,1′‐biaryls bearing fluoro substituents at the 2′, 3′, 4′, and/or 5′ positions, in the presence of heteroarenes and a palladium catalyst, C2′‐heteroarylated 1,1′‐biaryls derivatives are formed. In the course of this coupling reaction, the created CC bond arises from the functionalization of two CH bonds, with the bromide C2‐substituent behaving as a traceless directing group. This method allows to activate regioselectively of the CH bond at the C2′‐position of the polyfluorobenzene ring, even in the presence of a more reactive CH bond on this ring. This approach is synthetically attractive for the heteroarylation of the C2′‐position of 2‐bromo‐1,1′‐biphenyls, since preparing 2‐bromo‐1,1′‐biphenyls with fluoro substituents on the same ring as the bromo substituent is challenging. Moreover, this procedure employs an easily available air‐stable catalyst and an inexpensive base.