C([O:3][C:4](=[O:17])[CH2:5][CH:6]1[CH2:14][C:13]2[C:8](=[CH:9][C:10]([Br:15])=[CH:11][CH:12]=2)[C:7]1=[O:16])C.C(NB)(C)(C)C.[OH-].[Na+]>C1COCC1>[Br:15][C:10]1[CH:9]=[C:8]2[C:13]([CH2:14][CH:6]([CH2:5][C:4]([OH:17])=[O:3])[CH:7]2[OH:16])=[CH:12][CH:11]=1The product from Example 52A in THF was treated with tert-butylaminoborane (1.18 g, 13.5 mmol) and heated at 40-45° C. for 2.5 hours. The mixture was treated with sodium hydroxide solution (1.8 g in water, 40 mL) and heating was continued for 30 minutes. The mixture was allowed to cool to room temperature and the aqueous layer was separated. The organic layer was diluted with isopropyl acetate (40 mL) and water (40 mL) and combined with the aqueous layer. The solution was cooled to 0° C. and the pH was adjusted to 2 by addition of concentrated hydrochloric acid. The mixture was filtered and the fitler cake dried at room temperature. The solid was slurried in dichloromethane (6 mL), refiltered, and redried to provide the title compound.
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