[CH3:1][O:2][C:3]1[CH:12]=[C:11]2[C:6]([CH:7]=[C:8]([C:13]([OH:15])=O)[CH:9]=[N:10]2)=[CH:5][CH:4]=1.Cl.[CH3:17][NH:18][O:19][CH3:20].C(N(CC)CC)C.F[P-](F)(F)(F)(F)F.Br[P+](N1CCCC1)(N1CCCC1)N1CCCC1>ClCCl>[CH3:20][O:19][N:18]([CH3:17])[C:13]([C:8]1[CH:9]=[N:10][C:11]2[C:6]([CH:7]=1)=[CH:5][CH:4]=[C:3]([O:2][CH3:1])[CH:12]=2)=[O:15]
To a suspension of the intermediate from step D (1.5 mmol) and N,O-dimethyhydroxylamine hydrochloride (219 mg, 2.25 mmol), in dichloromethane (20 mL) was added triethyl amine (1.04 mL, 7.5 mmol) followed by bromo(trispyrrolidin-1yl)phosphonium hexafluorophosphate (840 mg, 1.8 mmol). After stirring the reaction mixture at room temperature for 3 hours, it was quenched by the addition of 1N HCl (10 mL). The resulting mixture was extracted with DCM. The organic layer was washed with saturated NaHCO3 solution, dried over anhydrous Na2SO4, filtered and concentrated in vacuo. The residue was purified by flash chromatography using 70% ethyl acetate-hexanes. 1H NMR (500 MHz, CDCl3): 9.15 (d, J=1.8 Hz, 1H), 8.5 (d, J=1.8 Hz, 1H), 8.0 (s, 1H), 7.7 (d, J=9.0 Hz, 1H), 7.43 (d, J=2.2 Hz, 1H), 7.24 (dd, J=2.5, 9.0 Hz, 1H), 3.96 (s, 3H), 3.57 (s, 3H), 3.43 (s, 3H). LC-MS: 1.6 min; (M+H)=247.1.
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