Palladium(II)-Catalyzed Nondirected C(sp²)-H Alkoxycarbonylation of Arenes

Aromatic carboxylic acid derivatives are ubiquitous structural motifs in organic chemistry, which find widespread use as synthetic intermediates or target compounds for various applications. An ideal way to access these compounds is by C-H functionalization of a simple arene with a C1-building block like CO. State of the art methods, however, require the use of prefunctionalized arenes or substrates bearing directing groups, which negatively impact the step economy and/or significantly limit the scope of such processes. Herein we describe Pd-catalysts for the nondirected C-H alkoxycarbonylation of simple arenes. The protocol offers a highly efficient approach toward the synthesis of aromatic esters and enables the functionalization of a broad range of substrates. The predominantly sterically controlled regioselectivity renders the process complementary to electrophilic aromatic substitution reactions. We demonstrate the synthetic versatility of the obtained products to access diverse classes of compounds and present mechanistic studies to derive a plausible reaction mechanism.