Efficient Synthesis of Various Benzoxazinones Using K2CO3/H2O in [Omim][BF4] Ionic Liquid

Synthesis of various derivatives of 2H-benzo[b][1,4]oxazin-3(4H)-one is efficiently carried out starting from the corresponding o-aminophenols and 2-bromoalkanoates. Reactions take place chemoselectively at room temperature catalyzed by K2CO3 and H2O in [omim][BF4] ionic liquid. At the end of the reactions, products are separated from the mixtures by ethereal extraction and the ionic liquid is recovered and recycled into the next reactions without noticeable loss of its activity. NMR experiments show no obvious changes in the structure of the ionic liquid after several reuses.