Synthesis of Ladder-Type π-Conjugated Heteroacenes via Palladium-Catalyzed Double N-Arylation and Intramolecular O-Arylation
2007; American Chemical Society; Volume: 72; Issue: 14 Linguagem: Inglês
10.1021/jo070427p
ISSN1520-6904
AutoresKeiko Kawaguchi, Koji Nakano, Kyoko Nozaki,
Tópico(s)Catalytic C–H Functionalization Methods
ResumoLadder-type heteroacenes containing pyrrole or furan rings, indolo[3,2-b]carbazoles and dibenzo[d,d']benzo[1,2-b:4,5-b']difurans, were effectively synthesized from the common intermediates, 2,5-bis(o-chloroaryl)hydroquinones. The key reactions are palladium-catalyzed double N-arylation of aniline and intramolecular O-arylation, which enable regioselective ring closure. In addition to the parent indolo[3,2-b]carbazole and dibenzo[d,d']benzo[1,2-b:4,5-b']difuran, their derivatives with an alkyl or cyano group were first synthesized. Photophysical and electrochemical studies showed that the obtained heteroacenes have lower HOMO energy levels and larger band gaps than the corresponding hydrocarbon acene, pentacene. An X-ray analysis of dibenzo[d,d']benzo[1,2-b:4,5-b']difuran revealed that it was packed in herringbone fashion.
Referência(s)