Preparation of 7-Alkylamino-2-methylquinoline-5,8-diones^†

Several novel 7-alkylamino-2-methylquinoline-5,8-diones (2) were synthesized from 2,5-dimethoxyaniline in five steps via the Skraup reaction followed by demethylations, oxidative bromination, amination, and debromination. We have achieved an unusual hydrobromic acid catalyzed debromination reactions of several 6-bromo-7-alkylamino-2-methylquinoline-5,8-diones, giving 7-alkylamino-2-methylquinoline-5,8-diones in good yields.