[NH2:1][C:2]1[CH:3]=[C:4]([C:8](=[NH:11])[NH:9][OH:10])[CH:5]=[CH:6][CH:7]=1.[H-].[Na+].[C:14](OC)(=O)[CH3:15].O>O1CCCC1>[CH3:14][C:15]1[O:10][N:9]=[C:8]([C:4]2[CH:3]=[C:2]([CH:7]=[CH:6][CH:5]=2)[NH2:1])[N:11]=1To a stirred solution of Intermediate 18 (5.3 g) in dry tetrahydrofuran (50 ml) was added 4 Å molecular sieves, followed by sodium hydride (60% dispersion in mineral oil; 1.5 g) and the mixture heated at 65° C. for 30 min. After cooling to room temperature methyl acetate (2.8 ml) was added and the mixture heated under reflux for 16 h. After cooling to 20° C. the mixture was added to water (100 ml) and extracted with ethyl acetate. The combined organic layers were washed with brine, dried over magnesium sulphate and concentrated in vacuo. The residue was purified by chromatography on silica gel, eluting with dichloromethane to give the title compound as a white solid (4.0 g).
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