Ligand-To-Copper Charge Transfer: A Single Vessel Decarboxylative Halogenation and Ullmann Cross-Coupling of (Hetero)Aryl Acids

Abstract

This thesis reports a single-vessel, copper-catalyzed transformation of both heteroaryl carboxylic acids and aryl carboxylic acids to final C–N coupled products through the activation of (hetero)aryl halide intermediates. Whereas classic coupling chemistry has been limited to the use of non-naturally abundant materials like aryl halides, this process makes use of (hetero)aryl carboxylic acids through a photochemical, copper-catalyzed ligand-to-metal charge transfer (LMCT) process to form both heteroaryl bromides and aryl iodides through halogen atom transfers. Unlike past aryl carboxylic acid chemistry, this process proceeds under mild conditions and requires no prior synthesis steps. After halogenation, the (hetero)aryl intermediates are readily able to undergo amination through copper-catalyzed, Ullmann-Goldberg type chemistry. This two-step, single-vessel aromatic decarboxylation amination reaction represents one of the first successful C–N coupling processes that utilize elusive (heteroaryl)aryl carboxylic acids by using LMCT chemistry.