A new method is developed for efficient and chemoselective synthesis of benzo[1,4]oxazineone derivatives. By the choice of an appropriate ionic liquid, the process is directed towards selective O- or N-alkylation to give the desired isomeric structures, as the major product of the reaction. In the presence of choline hydroxide, benzo[1,4]oxazine-3-one derivatives are formed, while by using choline fluoride, the corresponding benzo[1,4]oxazine-2-ones are obtained. The latter pathway would be facilitated for sluggish reactants by in situ use of an alkyl halide.