General method for the synthesis of substituted phenanthridin-6(5H)-ones using a KOH-mediated anionic ring closure as the key step

Substituted phenanthridin-6(5H)-ones were obtained in a two-step procedure involving a Suzuki cross-coupling reaction followed by a KOH-mediated anionic ring closure. The influence of the nature and the position of the substituents on the cyclization step were studied. This methodology offers a general and practical route to diversely substituted phenanthridin-6(5H)-ones.