[CH3:1][C:2]1[C:6]2[CH:7]=[CH:8][CH:9]=[C:10]([CH3:11])[C:5]=2[O:4][N:3]=1.[N+:12]([O-])([OH:14])=[O:13]>OS(O)(=O)=O.O>[CH3:1][C:2]1[C:6]2[CH:7]=[C:8]([N+:12]([O-:14])=[O:13])[CH:9]=[C:10]([CH3:11])[C:5]=2[O:4][N:3]=13,7-dimethylbenzo[d]isoxazole (Step 46.4) (2 g, 12.77 mmol) was dissolved in H2SO4 (5 mL), cooled down and stirred at 0° C. HNO3 (0.878 mL, 12.77 mmol) was slowly added and the resulting mixture was stirred at 0° C. for 1 hr. The reaction was diluted with water (60 mL) and extracted three times with CH2Cl2. The combined organic layers were washed with NaHCO3 solution and brine, dried over MgSO4, filtered and concentrated under reduced pressure. The resulting yellow solid was triturated with Et2O, filtrated off, washed with Et2O and dried to afford the title product (1.86 g, 9.29 mmol, 73% yield) as yellow solid. tR: 0.98 min (LC-MS 2); ESI-MS: 193 [M+H]+.
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