Hypervalent Activation as a Key Step for Dehydrogenative ortho CC Coupling of Iodoarenes

Building on earlier results, a direct metal‐free α‐ arylation of substituted cyclic 1,3‐diones using ArI(O₂CCF₃)₂ reagents has been developed; unlike other arylative approaches, the arylated products retain the iodine substituent ortho to the newly formed C?C bond. The mechanism is explored by using DFT calculations, which show a vanishingly small activation barrier for the C?C bond‐forming step. In fact, taking advantage of an efficient in situ hypervalent activation, the iodoarenes are shown to undergo a cross‐ dehydrogenative C?C coupling at the C?H ortho to the iodine. When Oxone is used as terminal oxidant, the process is found to benefit from a rapid initial formation of the hypervalent ArI(OR)₂ species and the sulfate‐accelerated final coupling with a ketone. This method complements the ipso selectivity obtained in the metal‐catalyzed α‐arylation of carbonyl compounds.