[H-].[Na+].[C:3]([O:7][C:8]([NH:10][CH2:11][CH2:12]/[CH:13]=[CH:14]/[C:15]1[CH:16]=[N:17][CH:18]=[N:19][CH:20]=1)=[O:9])([CH3:6])([CH3:5])[CH3:4].[CH:21](NC(C)C)(C)C.IC>COCCOC.O.CN(C=O)C>[CH3:21][N:10]([C:8]([O:7][C:3]([CH3:6])([CH3:4])[CH3:5])=[O:9])[CH2:11][CH2:12]/[CH:13]=[CH:14]/[C:15]1[CH:16]=[N:17][CH:18]=[N:19][CH:20]=1
Under a nitrogen atmosphere, sodium hydride (0.78 g, 19.5 mmol, 60% dispersion in oil) was added to a stirring solution of IV (0.50 g, 2.0 mmol), 1,2-dimethoxyethane (20 mL), DMF (25 mL), and a trace of diisopropylamine. The mixture was stirred at ambient temperature for 45 rain, and a solution of iodomethane (2.59 g, 18.3 mmol) in 1,2-dimethoxyethane (5 mL) was added. The mixture was stirred at ambient temperature for 3 days, cooled, and water (25 mL) was added dropwise. The mixture was diluted with water (200 mL) and extracted with chloroform (7×50 mL). All chloroform extracts were combined, dried (Na2SO4), filtered, and concentrated by rotary evaporation. The residue was dried under high vacuum at ambient temperature to give a red-brown oil. The oil was chromatographed on silica gel (50 g), elating with ethyl acetate. Selected fractions were combined, concentrated by rotary evaporation, and dried under high vacuum at ambient temperature to give compound V as a light yellow oil (0.40 g, 76.1%).
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