Synthesis of Aza[n]phenacenes (n = 4–6) via Photocyclodehydrochlorination of 2‑Chloro‑N‑aryl-1-naphthamides

A novel methodology for the synthesis of aza­[n]­phenacenes was successfully developed utilizing photocyclodehydrochlorination reaction of 2-chloro-N-aryl-1-naphthamides. In these key intermediates, the factors influencing the photoreaction were studied. The target aza­[n]­phenacenes were obtained by triflation or chlorination from prepared phenanthridinones, followed by hydrogenation. The introduction of a nitrogen atom into a phenacene skeleton induced changes in the physicochemical properties. The important properties of prepared aza­[n]­phenacenes (n = 4–6) were studied experimentally and by density functional theory calculations and were compared to those of their carbo analogues. Furthermore, some important features of the crystalline aza­[n]­phenacenes were investigated, including intermolecular interaction in the crystal lattice and the increased solubility or decreased melting points.