[CH:1]([N:4]1[C:8]([C:9]2[N:18]=[C:17]3[N:11]([CH2:12][CH2:13][O:14][C:15]4[CH:22]=[C:21]([O:23]C)[N:20]=[CH:19][C:16]=43)[CH:10]=2)=[N:7][CH:6]=[N:5]1)([CH3:3])[CH3:2].Br>C(O)(=O)C>[CH:1]([N:4]1[C:8]([C:9]2[N:18]=[C:17]3[N:11]([CH2:12][CH2:13][O:14][C:15]4[CH:22]=[C:21]([OH:23])[N:20]=[CH:19][C:16]=43)[CH:10]=2)=[N:7][CH:6]=[N:5]1)([CH3:3])[CH3:2]A solution of 2-(2-isopropyl-2H-[1,2,4]triazol-3-yl)-8-methoxy-4,5-dihydro-6-oxa-1,3a,9-triaza-benzo[e]azulene (1.0 g, 2.97 mmol) in acetic acid (40 mL) was treated with 48% aqueous HBr (37.7 mL) and heated at 80° C. for 5 h before being concentrated in vacuo. The resultant residue was suspended in water (60 mL) and pH adjusted to 6 using 5N aqueous NaOH. The precipitate formed was filtered off, washed with water then dried in vacuo. The resultant solid was triturated in acetone to give 2-(2-Isopropyl-2H-[1,2,4]triazol-3-yl)-4,5-dihydro-6-oxa-1,3a,9-triaza-benzo[e]azulen-8-ol as a beige solid (3.58 g, 69%). LCMS RT=2.04 min, [M+H]+ =313. 1H NMR 400 MHz (DMSO-d6) δ: 8.42 (1H, s), 7.90 (1H, s), 7.83 (1H, s), 5.84 (1H, s), 5.78 (1H, m), 4.71-4.30 (4H, m), 1.45 (6H, d, J=6.60 Hz).
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