105807-83-8

85160-83-4

105807-83-8

General procedure for the synthesis of 7-amino-2,2-dimethyl-2H-benzo[b][1,4]oxazin-3(4H)-one from 2,2-dimethyl-7-nitro-2H-benzo[b][1,4]oxazine-3(4H)-one: 100 mM of mixed solvent (EtOH:H2O = 3:1) was added to the reaction flask and stirred at room temperature. 30 mM of 2,2-dimethyl-7-nitro-2H-benzo[b][1,4]oxazin-3(4H)-one, 10 mM of ammonium chloride and 30 mM of iron powder were added sequentially. The reaction mixture was heated to 90 °C and refluxed for 1-2 hours. The progress of the reaction was monitored by TLC. After completion of the reaction, the excess iron powder was removed by filtration while hot. After cooling, the solvent was removed by distillation under reduced pressure. The pH of the residual solids was adjusted to 10 with aqueous potassium carbonate to induce precipitation of the solids, followed by filtration. The filter cake was washed with cooling water and dried under vacuum to give a pure intermediate of 4.23 g yellow powder in 73.4% yield. The intermediate did not require further purification and could be used directly in the subsequent reaction.