[CH3:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[CH:13]=[CH:12][C:11]([CH2:14][CH2:15][CH2:16][OH:17])=[CH:10][CH:9]=2)=[N:6][CH:7]=1.CC1(C)N([O])C(C)(C)CCC1.[Br-].[K+].Cl[O-].[Na+].C(=O)(O)[O-].[Na+]>ClCCl>[CH3:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[CH:13]=[CH:12][C:11]([CH2:14][CH2:15][CH:16]=[O:17])=[CH:10][CH:9]=2)=[N:6][CH:7]=1To a stirred solution of the compound obtained from step d above (1.4 g) in dichloromethane (20 mL), 2,2,6,6-tetramethylpiperidine N-oxyl (9.6 mg) and potassium bromide (73.4 mg) were added at 0° C. under nitrogen atmosphere. Sodium hypochlorite (13.7 mL, 4% solution) was added at pH 8-9 (maintained by adding aqueous sodium bicarbonate solution). The reaction was stirred for 20 minutes at 0° C. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The combined organic layers were washed with saturated aqueous sodium bicarbonate solution, water, and brine. The organic layer was dried over anhydrous sodium sulphate, filtered, and concentrated under reduced pressure to afford the title compound (0.9 g).
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