Cu<sub>2</sub>O/Cs<sub>2</sub>CO<sub>3</sub>/DMF: An efficient catalytic system for <i>N</i>-arylation of imidazole with aryl halides under ligand-free conditions WangXiaochuang WangMeiji XieJianwei 2017 <p>A ligand-free Cu-catalyzed protocol for the Ullmann-type <i>N</i>-arylation of <i>N</i>-containing heterocycles with aryl or heteroaryl iodides and bromides has been established. A broad range of functional groups is well tolerated on both of the cross-coupling partners, producing the desired products in good to excellent yields.</p>