Selective ortho-Metalation of a Fluoroarene with Knochel–Hauser Base and Reactions with Various Electrophiles

Selective ortho -metalation of 1-bromo-2-(1,1-difluoroethyl)-4-fluorobenzene was achieved with the Knochel–Hauser base (TMPMgCl·LiCl) in position 5 of the aromatic ring. The magnesiated intermediate was reacted with a variety of electrophiles to obtain the products in good yields. The work was successfully extended to a Negishi coupling, after transmetalation with ZnCl 2 and Pd-catalyzed reaction with 4-iodotoluene.