C([S:4][CH2:5][CH:6]([NH:12][C:13]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14])[CH2:7][S:8]C(=O)C)(=O)C.[OH-].[Na+].II>C(O)C.ClCCl>[C:16]([O:15][C:13](=[O:14])[NH:12][CH:6]1[CH2:7][S:8][S:4][CH2:5]1)([CH3:19])([CH3:18])[CH3:17]A solution of thioacetic acid S-(3-acetylsulfanyl-2-tert-butoxycarbonylamino-propyl) ester (330 mg) in ethanol (5 ml) was treated with 2.5 ml of 1N sodium hydroxide for 1 hour at room temperature. The yellow solid turned green-brown. The reaction mixture was diluted with dichloromethane (25 ml) and then an aqueous solution of 0.1M iodine (10 ml) was added dropwise. The reaction mixture was stirred at room temperature for 1 hour and quenched by addition of 1M sodium bisulfite solution. The organic layer was separated, washed with water, dried over sodium sulfate and the solvent evaporated in vacuo to afford the title product (170 mg). 1H-NMR (CDCl3, 400 MHz): 5.00 (br s, 1H), 4.90 (m, 1H), 3.15 (d, 2H), 3.05 (d, 2H), 1.40 (s, 9H).
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