Solvent-Free Buchwald-Hartwig (Hetero)arylation of Anilines, Diarylamines, and Dialkylamines Mediated by Expanded-Ring N-Heterocyclic Carbene Palladium Complexes

A highly efficient solvent-free protocol for the Buchwald-Hartwig (hetero)arylation of anilines, diarylamines, and dialkylamines mediated by the expanded-ring N-heterocyclic carbene palladium complex (THP-Dipp)Pd(cinn)Cl [THP-Dipp = 1,3-bis(2,6-diisopropylphenyl)-3,4,5,6-tetrahydropyrimidin-2-yl-idene; cinn = cinnamyl, 3-phenylallyl] was developed. The catalytic protocol was efficient for the coupling of amines and (hetero)aryl chlorides and bromides bearing donor, acceptor, and bulky substituents.