C([O:3][C:4](=[O:33])[CH2:5][CH2:6][CH2:7][N:8]1[CH2:16][CH2:15][N:14]([CH2:17][C:18]([O:20]C(C)(C)C)=[O:19])[CH2:13][CH2:12][N:11]([CH2:25][C:26]([O:28]C(C)(C)C)=[O:27])[CH2:10][CH2:9]1)C.[Li+].[OH-]>C(O)C>[C:18]([CH2:17][N:14]1[CH2:13][CH2:12][N:11]([CH2:25][C:26]([OH:28])=[O:27])[CH2:10][CH2:9][N:8]([CH2:7][CH2:6][CH2:5][C:4]([OH:33])=[O:3])[CH2:16][CH2:15]1)([OH:20])=[O:19]The ethanol liquid (0.5 mL) of the 4,7-bis(tert-butoxycarbonylmethyl)-1,4,7-triazonane-1-butyric acid ethyl ester (0.025 g, 0.0529 mmol) prepared at Step 1 was added with LiOH (0.0038 g, 0.159 mmol), followed by reaction at 50° C. for 24 hr. After confirming completion of the hydrolysis with ESI-mass, the reacted mixture was filtered through the Whatman syringe filter (0.45 μm) and dried under reduced pressure. The product was separated with RP-HPLC (10 mM HCl/EtOH; concentration increase from 0 to 40% for 20 min), and the filtrate underwent lyophilization to give final product.
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