Iodane-Guided C-H Cleavage to Synthesize Densely Functionalized Arenes

We describe a strategy for the iodane-guided functionalization of sterically congested C-H bonds, which is distinct from electronic, steric or proximity guided C-H functionalization methods. Readily accessible aryl(Mes)iodonium salts serve as the starting materials in these reactions and produce complex 1,2,3,4-substituted arenes via aryne intermediates. This approach is especially powerful when coupled with the innate C-H functionalization reactivity of simple arenes, to replace two C-H bonds with two C-C or C-heteroatom bonds while over-riding steric effects that typically inhibit such reactions. DFT stud-ies reveal a contribution of inductive, resonance, and steric effects on the regioselectivity of C-H cleavage and aryne generatation.