C([O:4][CH2:5][C:6]1[O:10][N:9]=[C:8]([N:11]2[CH2:16][CH2:15][N:14]([C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18])[CH2:13][CH2:12]2)[N:7]=1)(=O)C.[OH-].[Na+]>CO>[OH:4][CH2:5][C:6]1[O:10][N:9]=[C:8]([N:11]2[CH2:12][CH2:13][N:14]([C:17]([O:19][C:20]([CH3:23])([CH3:22])[CH3:21])=[O:18])[CH2:15][CH2:16]2)[N:7]=11,1-Dimethylethyl 4-{5-[(acetoxy)methyl]-1,2,4-oxadiazol-3-yl}piperazine-1-carboxylate (13.57 g, 41.6 mmol) was dissolved in methanol (100 mL) followed by addition of aqueous sodium hydroxide (4M, 10.4 mL) and the mixture was stirred for 30 minutes at room temperature. The reaction mixture was then concentrated in vacuo and the residue partitioned with ethyl acetate and 0.1M aqueous hydrochloric acid. The organic layer was then washed with saturated aqueous sodium chloride then dried over anhydrous magnesium sulfate. Filtration and concentration afforded 1,1-dimethylethyl 4-[5-(hydroxymethyl)-1,2,4-oxadiazol-3-yl]piperazine-1-carboxylate (10.51 g, 89% yield) as a colorless crystalline solid. 1H-NMR (400 MHz, CDCl3): 4.75 (s, 2H), 3.53-3.50 (m, 4H), 3.44-3.42 (m, 4H), 3.20 (br s, 1H), 1.48 (s, 9H).
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