Friedländer approach for the incorporation of 6-bromoquinoline into novel chelating ligands.

Nitration of 3-bromobenzaldehyde followed by sodium dithionite reduction provides 5-bromo-2-aminobenzaldehyde, which undergoes the Friedländer condensation with a variety of enolizable ketones to afford bidentate and tridentate 6-bromoquinoline derivatives. These species may be dimerized with Ni(0) to form biquinolines or treated under Sonogashira conditions to afford 6-alkynyl derivatives. Examination of optical properties indicate an unusually high emission quantum yield for 6,6'-biquinolines. [structure: see text]