[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][CH:11](OS(C)(=O)=O)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[H-].[Na+].[NH:21]1[CH:25]=[CH:24][N:23]=[CH:22]1>CN(C=O)C>[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][CH:11]([N:21]2[CH:25]=[CH:24][N:23]=[CH:22]2)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]A solution of the title compound from Step B (4.0 g, 14.32 mmoles) in DMF (120 mL) was added to a stirred solution of NaH (0.52 g, 21.66 mmoles) and imidazole (1.46 g, 21.47 mmoles) in DMF (20 mL) under nitrogen atmosphere. The mixture was stirred at 60° C. for 16 h. DMF was evaporated in vacuo. The resulting crude product was extracted with CH2Cl2 and the extract was successively washed with water and brine, and the CH2Cl2 was evaporated to leave the title residue which was chromatographed on silica gel using 3% (10% cone NH4OH in methanol)-CH2Cl2 as eluant to give the title compound (0.94 g, 26%). FABMS (M+1)=252; δH (CDCl3) 1.4 (s, 9H), 1.6-1.8 (m, 2H), 2.0 (dd, 2H), 2.8 (dt, 2H), 4.05 (m, 1H), 4.2 m, 2H), 6.9 (s, 1H), 7.0 (s, 1H), 7.65 (s, 1H).
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