tert-Butoxide-Mediated Synthesis of 3,4′-Biquinolines from 2-Aminochalcones

A novel protocol to synthesize 3,4’-biquinolines from 2-aminochalcones in the presence of a stoichiometric amount of sodium tert-butoxide as the nucleophilic promotor was developed. Conjugate addition of tert-butoxide to 2-aminochalcones provided the corresponding enolates, which underwent Michael addition to another molecule of 2-aminochalcone to afford a dimeric species of 2-aminochalcones. Subsequent cyclization between the amino and carbonyl groups followed by aromatization provides 3,4’-biquinoline products. Various 2-aminochalcones were submitted to this protocol and the desired 3,4’-biquinoline products were obtained in good to high yields in a short reaction time. (Figure presented.).