Synthesis of Aza[<i>n</i>]phenacenes (<i>n</i> = 4–6) via Photocyclodehydrochlorination of 2-Chloro-<i>N</i>-aryl-1-naphthamides
Lubomír Váňa, Martin Jakubec, Ján Sýkora, Ivana Cı́sařová, Jan Storch, Vladimı́r Cı́rkva
Abstract
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.