Synthesis of unsymmetrical benzils using N-heterocyclic carbene catalysis

In this paper, we propose a novel and efficient method for the preparation of various unsymmetrical benzils. We first demonstrate the nucleophilic aroylation of N-phenylbenzimidoyl chlorides with aromatic aldehydes using N-heterocyclic carbene as the catalyst to afford 1-aryl-2-phenyl-2-(phenylimino)ethanones. These iminoethanones were then converted to 1,2-diaryl-1,2-diketones by acid-promoted hydrolysis.