Metal–N-Heterocyclic Carbene Complexes in Buchwald–Hartwig Amination Reactions

We present a comprehensive overview of the Buchwald–Hartwig amination, one of the most useful methods for C–N bond formation, mediated by NHC–transition-metal-complexes, covering the literature since 1999 (the first report on Buchwald–Hartwig amination by Nolan et al.) through December 2024. Palladium– and nickel–N-heterocyclic carbene (NHC) complexes are key contributors to Buchwald–Hartwig amination and are thoroughly discussed in this review, along with examples of cobalt and rhodium–NHC complexes. Apart from the conventional aryl/alkyl amines and aryl halides coupling, participation of versatile and challenging functional groups like pseudohalides, amides, ester, sulfoxides, unactivated aryl sulfamates, carbamates, pivalates, as well as novel electrophiles, such as aryl fluorides, methyl ethers, and silyloxyarenes, are also presented. The Reader is provided with an overview of the key role of metal–NHC complexes, their crucial role in constructing carbon–nitrogen bonds, and their importance in medicinal and materials chemistries as well as in drug discovery.