[CH3:1][N:2]([CH2:4][CH:5]1[CH2:10][CH2:9][C:8](=[O:11])[CH2:7][C:6]1([OH:20])[C:12]1[CH:17]=[CH:16][CH:15]=[C:14]([O:18][CH3:19])[CH:13]=1)[CH3:3].[BH4-].[Na+].[Cl-].[NH4+].[OH-].[Na+]>O1CCCC1.C(O)C>[CH3:3][N:2]([CH2:4][CH:5]1[C:6]([C:12]2[CH:17]=[CH:16][CH:15]=[C:14]([O:18][CH3:19])[CH:13]=2)([OH:20])[CH2:7][CH:8]([OH:11])[CH2:9][CH2:10]1)[CH3:1]A solution of 10 g (0.036 mol) of the crude product (IV) in 36.5 ml tetrahydrofuran was added dropwise at +2° C. with stirring to a solution of 1.36 g (0.036 mol, 1 equiv.) sodium borohydride in 15 ml ethanol and 36.5 ml tetrahydrofuran. Once the crude product solution had been completely added the mixture was then stirred for 60 to 90 minutes at +15° C. 25 ml aqueous ammonium chloride solution (10% w/w) were then added and alkalized with 5 ml sodium hydroxide solution (32%) to pH 12. After being extracted twice with 50 ml ethyl acetate, the combined phases were dried over magnesium sulfate and evaporated in vacuo. 10 g crude mixture was obtained in this case.
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