[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([CH:6]=[CH:7][C:8]([CH:12]=[CH:13][C:14]3[CH:15]=[C:16]([CH:26]=[CH:27][CH:28]=3)[O:17][CH2:18][CH2:19][CH2:20][C:21]([O:23]CC)=[O:22])=[N:9]2)=[CH:4][CH:3]=1.[OH-].[Na+:30]>C1COCC1.CCO>[Na+:30].[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([CH:6]=[CH:7][C:8]([C:12]#[C:13][C:14]3[CH:15]=[C:16]([CH:26]=[CH:27][CH:28]=3)[O:17][CH2:18][CH2:19][CH2:20][C:21]([O-:23])=[O:22])=[N:9]2)=[CH:4][CH:3]=1To a solution of the ethyl ester from Step 4 (380 mg) in THF (4 mL) and EtOH (2 mL) was added 2N NaOH (0.65 mL) and the mixture was stirred overnight at room temperature. The reaction mixture was evaporated to dryness and passed through a neutral XAD-8 resin, eluting with H2O and then with EtOH, to afford the title compound as a white solid: m.p. 250° C. (d).
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