General Method for the Suzuki–Miyaura Cross-Coupling of Amides Using Commercially Available, Air- and Moisture-Stable Palladium/NHC (NHC =<i>N</i>-Heterocyclic Carbene) Complexes

Abstract

The direct Suzuki–Miyaura cross-coupling of amides catalyzed by Pd-NHC complexes is reported. Using a single protocol, commercially available, air- and moisture-stable (NHC)Pd(R-allyl)Cl complexes can effect Suzuki–Miyaura cross-coupling of a wide range of amides with arylboronic acids in very good yields. The studies described herein represent the use of versatile Pd-NHC complexes as catalysts for transition-metal-catalyzed cross-coupling of amides by N–C bond activation. The Pd-NHC catalysts provide a significant improvement over all current Pd-PR3 systems employed for the amide N–C bond activation. Mechanistic studies provide strong support for the development of a unified reactivity scale of the amide bond for the generation of acyl-metal intermediates.