[CH3:1][NH:2][C:3](=[O:19])[CH2:4][CH2:5][CH2:6][CH2:7][C:8]1[CH:13]=[CH:12][C:11]([CH2:14][CH2:15][CH2:16][CH2:17][NH2:18])=[CH:10][N:9]=1.[H-].[Na+]>>[CH3:1][NH:2][C:3](=[O:19])[CH2:4][CH2:5][CH2:6][CH2:7][C:8]1[CH:13]=[CH:12][C:11]2[CH2:14][CH2:15][CH2:16][CH2:17][NH:18][C:10]=2[N:9]=1A mixture of 8-7 (24 g, 91.2 mmol) and NaH (10.9 g of a 60% weight dispersion in mineral oil, 273 mmol) in xylenes (500 mL) was purged with argon for 30 min, and then heated at reflux for 72 hours. The mixture was cooled, quenched with ethanol, diluted with 10% aqueous potassium carbonate and extracted with ethyl acetate. The organics were dried over MgSO4, and concentrated to an oil. The residue was chromatographed on silica gel (70:25:5 CHCl3/EtOAc/MeOH/H2O) to give 8-8 as a white solid.
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