7,12‐Dihydrobenzo[de]indolo[3,2‐b]quinoline: Unique Reactivity and Redox Interconversion

Abstract

AbstractAcetyl‐substituted 7,12‐dihydrobenzo[de]indolo[3,2‐b]quinoline was developed as a N‐substituted polycyclic heteroaromatic molecule via Pd‐catalyzed cyclo‐isomerization of an alkyne precursor, followed by intramolecular Goldberg amination. This compound showed unique reactivity, notably, base‐mediated deacylative oxygenation and photo‐Fries rearrangement. A series of products exhibited characteristic electronic properties based on the redox state of the corresponding nitrogen atoms. The photo‐rearranged product, which possesses a 1,2‐diaminoethene substructure, akin to the redox functionality of the natural flavin adenine dinucleotide, underwent reversible interconversion with the corresponding oxidized form. The efficient stabilization of the highly electron‐rich 7,12‐dihydrobenzo[de]indolo[3,2‐b]quinoline skeleton was ascribed to the electron‐withdrawing effect, intramolecular hydrogen bonding of the acetyl group, and local aromatic stabilization in the indole moiety.