TIPS-Ethynylated Naphthodiquinoline and Naphthodiacridine: Novel Diazabisacenes.

The synthesis of two diazabisacenes is reported. A bisboronated naphthalene is Suzuki-coupled to substituted ethyl nicotinates, then cyclized via intramolecular Friedel-Crafts acylation. The resulting diketones are alkynylated and reduced to give the title compounds, bis(TIPS-ethynyl) substituted naphtho[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.