To a solution of 8-(5,5-dimethyl-[1,3,2]dioxaborinan-2-yl)-2-(2-isopropyl-2H-[1,2,4]triazol-3-yl)-4,5-dihydro-6-oxa-1,3a-diaza-benzo[e]azulene (473 mg, 1.16 mmol) in IMS (10 mL) was added hydroxylamine hydrochloride (242 mg, 0.39 mmol) and sodium hydroxide (186 mg, 4.65 mmol) and the reaction mixture stirred at RT for 18 h. Further quantities of hydroxylamine hydrochloride (242 mg, 0.39 mmol) and sodium hydroxide (186 mg, 4.65 mmol) were added and stirring continued for 3 h. The reaction mixture was diluted with ammonium chloride solution (20 mL, saturated) and extracted with ethyl acetate (3×10 mL). The combined organic extracts were dried (MgSO4), concentrated in vacuo and the resultant residue subjected to flash chromatography (SiO2, gradient 0-5% methanol in DCM) to yield 490 as a white solid (155 mg, 43%). 1H NMR (400 MHz, CDCl3) δ 8.29 (1H, d, J=8.4 Hz), 7.88 (1H, s), 7.59 (1H, s), 6.64 (1H, dd, J=8.4, 2.6 Hz), 6.48 (1H, d, J=2.6 Hz), 5.99 (1H, sept, J=6.7 Hz), 4.44-4.32 (4H, m), 1.58 (6H, d, J=6.7 Hz).
