Nickel-Catalyzed Direct Acylation of Aryl and Alkyl Bromides with Acylimidazoles

A modular method for the acylation of aryl and alkyl halides is reported herein. The transformation relies on acylimidazoles, easy-to-prepare and flexible species derived from abundant carboxylic acids, as viable cross-coupling partners for the Ni-catalyzed acylation. Careful examination revealed a remarkable mechanism: the amide C-N bond of primary and secondary imidazolides can be activated by single-electron reduction, representing a major departure from other reported amide C-N bond activation reactions. Extensive mechanistic studies also revealed an intriguing CO-extrusion-recombination phenomenon. This cross-coupling reaction between two electrophiles features a broad substrate scope bearing a wide gamut of functionalities. The practicality of this atypical transformation was demonstrated in the syntheses of 3-furyl natural products, which are difficult to access using traditional organometallic chemistry.