[NH:1]1[CH2:7][C:5](=[O:6])NC1=O.[CH2:8]([O:15][CH:16]1[CH2:21][CH2:20]C(=O)[CH2:18][CH2:17]1)[C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=1.S(=O)(=O)(O)[OH:24]>[OH-].[Ba+2].[OH-]>[NH2:1][C:7]1([C:5]([OH:6])=[O:24])[CH2:18][CH2:17][CH:16]([O:15][CH2:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=2)[CH2:21][CH2:20]1The hydantoin 42 is hydrolyzed by refluxing with 10 mL of a barium hydroxide solution (saturated at room temperature) for 16 h (Step 39). The solution is neutralized to pH 6 with 2N sulfuric acid and evaporated to dryness in vacuo. The residue is extracted with 50 mL of hot methanol, filtered, and washed with 50 mL of hot methanol. The methanol solutions are combined and evaporated.
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