[CH3:1][O:2][C:3](=[O:26])[C@H:4]([CH2:22][CH2:23][S:24][CH3:25])[NH:5][C:6](=[O:21])[C:7]1[CH:12]=[CH:11][C:10]([CH:13]=[O:14])=[CH:9][C:8]=1[C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1.[BH4-].[Na+]>C(O)C>[CH3:1][O:2][C:3](=[O:26])[C@H:4]([CH2:22][CH2:23][S:24][CH3:25])[NH:5][C:6](=[O:21])[C:7]1[CH:12]=[CH:11][C:10]([CH2:13][OH:14])=[CH:9][C:8]=1[C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1To a solution of the resultant compound from Example 16E in ethanol at 0° C. is added sodium borohydride (0.5 equivalent), and the reaction is stirred at 0° C. until TLC analysis shows the reaction to be complete. The reaction mixture is extracted with ether, which is washed with water and brine, dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The residue is then purified by column chromatography on silica gel to afford the title product.
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