2,4-Dihalogenoquinolines. Synthesis, orientation effects and 1H and 13C NMR spectral studies

Isomer ratios for the syntheses of 2,4-dichloroquinolines from meta-substituted and 3,4-disubstituted anilines are reported, a synthesis of 2,4-dibromoquinoline 1b is also described. The structures of certain bromination products 17 and 1f obtained from 4-hydroxy-2-quinolone have been revised. A thorough study of the 1H and 13C NMR spectra of a series of 2,4-dihalogenoquinolines is presented and the effects of the halogen substituents on JCH couplings are highlighted.