Ligand Development Enabled Cu-Catalyzed Coupling of (Hetero)aryl Chlorides and Ammonia with Higher Turnovers

Abstract

An oxalohydrazide derived from 2,7-di-tert-butylcarbazole was identified as a highly effective ligand in the copper-catalyzed coupling of (hetero)aryl chlorides with aqueous ammonia. This system enables the reaction to proceed smoothly with a catalyst loading as low as 0.1 mol % at 120 °C─the lowest loading ever reported for such metal-catalyzed transformations. The same catalytic system also allows coupling of (hetero)aryl chlorides at 80 °C and (hetero)aryl bromides at room temperature, each representing the lowest temperatures yet achieved for these coupling reactions.