DFT studies on the carboxylation of the C-H bond of heteroarenes by copper(I) complexes

In this study, we have used density functional theory to identify a new mechanism for the formation of carboxylate compounds from heteroarenes, such as benzoxazole, in the presence of copper catalysts. This new mechanism involves the formation of a carbene intermediate that is indirectly stabilized by the electron-releasing copper. This intermediate carbene can isomerize to the experimentally observed resting state of the catalytic cycle, but it is the intermediate carbene itself that has the greater reactivity toward CO ₂ and that leads to the final carboxylate product via a lower-energy pathway. Our findings demonstrate the importance of considering metal-stabilized carbenes in such reactions. Our findings also suggest that this carbene intermediate can act as a nucleophile in other organometallic reactions.