Spatial Anion Control on Palladium for Mild C–H Arylation of Arenes

C–H arylation of arenes without the use of directing groups is a challenge, even for simple molecules, such as benzene. We describe spatial anion control as a concept for the design of catalytic sites for C–H bond activation, thereby enabling nondirected C–H arylation of arenes at ambient temperature. The mild conditions enable late-stage structural diversification of biologically relevant small molecules, and site-selectivity complementary to that obtained with other methods of arene functionalization can be achieved. These results reveal the potential of spatial anion control in transition-metal catalysis for the functionalization of C–H bonds under mild conditions.