Investigations on 2,3′-Biquinoline. 17. Regioselectivity of the Halogenation of 2,3′-Biquinoline Derivatives

Abstract

A method has been developed for the synthesis of bromo and chloro derivatives of 2,3′-biquinoline and 2,3′-biquinolones based on the bromination and chlorination in various media. It was found that the bromination of 2,3′-biquinoline in strongly acidic medium occurred on the 2-quinoline fragment and in weak acid on the 3-quinoline and that it takes place via a stage of formation of a dihydro derivative. 1′-Alkyl-1′, 4′-dihydro-2,3′-biquinolin-4′-ones and 1′-alkyl-1′,2′-dihydro-2,3′-biquinolin-2′-ones are halogenated at position 6′.