Bimetallic Catalyzed Synthesis of 2-Arylindoles

A bimetallic synthesis of 2-arylindoles from alcohols and anilines is described. The dehydrogenation or oxidation of a secondary alcohol was performed by Ni-or Mn-catalyzed reactions, respectively. The formed ketone was converted into an imine intermediate that was later cyclized to the corresponding 2-arylindole by a Pd-catalyzed oxidative cyclization. A series of 2-arylindoles were prepared without isolation of the intermediates generated. The compatibility of the catalysts was investigated, and the optimized protocol opens room for the integration of Earth-abundant metals and palladium complexes to improve the sustainability of the synthesis of N-heterocycles.