[C:1]([O:5][C:6](=[O:22])[NH:7][CH2:8][CH2:9][NH:10][C:11]([NH:13][CH2:14][CH:15](OCC)OCC)=[O:12])([CH3:4])([CH3:3])[CH3:2].Cl.[OH-].[K+]>CO.O>[C:1]([O:5][C:6](=[O:22])[NH:7][CH2:8][CH2:9][N:10]1[CH:15]=[CH:14][NH:13][C:11]1=[O:12])([CH3:2])([CH3:3])[CH3:4]Dissolve {2-[3-(2,2-diethoxy-ethyl)-ureido]-ethyl}-carbamic acid tert-butyl ester (6.5 g, 20.35 mmol) in methanol (75 mL) and water (40 mL). To the reaction mixture add HCl (0.4 N, 50 mL) dropwise over 30 min. Stir the mixture overnight and neutralize by adding KOH (0.4 M, 50 mL), and concentrate in vacuo. Extract the residue in chloroform and wash with saturated aqueous sodium chloride, dry over MgSO4, filter and remove solvent on a rotovap to give a crude white solid. Purify by column chromatography 1% to 10% MeOH in dichloromethane to afford the pure product as a white solid (2.53 g, 11.13 mmol). GCMS (EI) m/z 227 M+.
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