C[O:2][C:3]([CH:5]1[C:9]2([CH2:14][CH2:13][CH2:12][CH2:11][CH2:10]2)[CH2:8][N:7]([C:15]([O:17][CH2:18][C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)=[O:16])[CH2:6]1)=[O:4].[OH-].[Na+]>O1CCOCC1.O>[CH2:18]([O:17][C:15]([N:7]1[CH2:6][CH:5]([C:3]([OH:4])=[O:2])[C:9]2([CH2:14][CH2:13][CH2:12][CH2:11][CH2:10]2)[CH2:8]1)=[O:16])[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1To a solution of (6) (300 mg; 0.9 mmol) in a mixture dioxane/water (6 mL; 9:1) was added a 2 M solution of NaOH (0.90 mL; 1.8 mmol). The reaction mixture was stirred at 35° C. for 6 hours. Solvents were removed in vacuo. The residue was diluted in water (15 mL) and was washed with diethyl ether (3×10 mL). The aqueous phase was acidified with 2N HCl and was extracted with ethyl acetate (3×15 mL). The ethyl acetate extracts were combined, dried over MgSO4, and concentrated to give 254 mg (0.8 mmol; 89%) of (7) as a colorless gum.
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