Decarboxylative Borylation and Cross-Coupling of (Hetero)aryl Acids Enabled by Copper Charge Transfer Catalysis
Nathan W. Dow, P. Scott Pedersen, Tiffany Q. Chen, David C. Blakemore, Anne‐Marie Dechert‐Schmitt, Thomas Knauber, David W. C. MacMillan
Abstract
We report a copper-catalyzed strategy for arylboronic ester synthesis that exploits photoinduced ligand-to-metal charge transfer (LMCT) to convert (hetero)aryl acids into aryl radicals amenable to ambient-temperature borylation. This near-UV process occurs under mild conditions, requires no prefunctionalization of the native acid, and operates broadly across diverse aryl, heteroaryl, and pharmaceutical substrates. We also report a one-pot procedure for decarboxylative cross-coupling that merges catalytic LMCT borylation and palladium-catalyzed Suzuki–Miyaura arylation, vinylation, or alkylation with organobromides to access a range of value-added products. The utility of these protocols is highlighted through the development of a heteroselective double-decarboxylative C(sp2)–C(sp2) coupling sequence, pairing copper-catalyzed LMCT borylation and halogenation processes of two distinct acids (including pharmaceutical substrates) with subsequent Suzuki–Miyaura cross-coupling.