Nickel-Catalyzed Esterification of Aliphatic Amides.

Recent studies have demonstrated that amides can be used in nickel-catalyzed reactions that lead to cleavage of the amide C-N bond, with formation of a C-C or C-heteroatom bond. However, the general scope of these methodologies has been restricted to amides where the carbonyl is directly attached to an arene or heteroarene. We now report the nickel-catalyzed esterification of amides derived from aliphatic carboxylic acids. The transformation requires only a slight excess of the alcohol nucleophile and is tolerant of heterocycles, substrates with epimerizable stereocenters, and sterically congested coupling partners. Moreover, a series of amide competition experiments establish selectivity principles that will aid future synthetic design. These studies overcome a critical limitation of current Ni-catalyzed amide couplings and are expected to further stimulate the use of amides as synthetic building blocks in C-N bond cleavage processes.