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

J Org Chem. 2021 Oct 1;86(19):13252-13264. doi: 10.1021/acs.joc.1c01113. Epub 2021 Sep 17.

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.