Transition-Metal-Free Decarboxylative Iodination: New Routes for Decarboxylative Oxidative Cross-Couplings

Constructing products of high synthetic value from inexpensive and abundant starting materials is of great importance. Aryl iodides are essential building blocks for the synthesis of functional molecules, and efficient methods for their synthesis from chemical feedstocks are highly sought after. Here we report a low-cost decarboxyl­ative iodin­ation that occurs simply from readily available benzoic acids and I2. The reaction is scalable and the scope and robustness of the reaction is thoroughly examined. Mechanistic studies suggest that this reaction does not proceed via a radical mechanism, which is in contrast to classical Hunsdiecker-type decarboxyl­ative halogen­ations. In addition, DFT studies allow comparisons to be made between our procedure and current transition-metal-catalyzed decarboxyl­ations. The utility of this procedure is demonstrated in its application to oxidative cross-couplings of aromatics via decarboxyl­ative/C–H or double decarboxyl­ative activations that use I2 as the terminal oxidant. This strategy allows the preparation of biaryls previously inaccessible via decarboxyl­ative methods and holds other advantages over existing decarboxyl­ative oxidative couplings, as stoichio­metric transition metals are avoided.