TIPS-Ethynylated Naphthodiquinoline and Naphthodiacridine: Novel Diazabisacenes.

The synthesis of two diazabisacenes is reported. A bisboronated naphthalene was Suzuki-coupled to substituted ethyl nicotinates, then cyclized by intramolecular Friedel-Crafts acylation. The resulting diketones were alkynylated and reduced to give the title compounds, bis(TIPS-ethynyl)-substituted naphtha[1,8-gh:5,4-g'h']diquinoline and naphtho[1,8-bc:5,4-b'c']diacridine. Nitrogen incorporation stabilizes the bisacenes with respect to oxidation compared to their consanguine nonaza analogs.