Metal-Free Synthesis of Benzo[a]phenanthridines from Aromatic Aldehydes, Cyclohexanones, and Aromatic Amines

Comprehensive Summary A three-component synthesis of benzo[alpha]phenanthridines from aromatic aldehydes, cyclohexanones, and aromatic amines has been developed, which is mediated by KI/DMSO/camphorsulfonic acid to afford a variety of functionalized benzo[alpha]phenanthridines in satisfactory yields. The present strategy provides a biaryl motif ortho to the nitrogen atom which has the potential to be used as ligand by further modification. With the advantages of readily available starting materials, transition-metal-free conditions, gram-scale synthesis, and broad substrate scope, this three-component protocol provides an efficient approach for the preparation of diverse benzo[alpha]phenanthridines.