C(OC([N:8]([CH2:18][CH2:19][C:20]1[CH:25]=[CH:24][C:23]([N+:26]([O-:28])=[O:27])=[CH:22][CH:21]=1)[CH2:9][CH2:10][NH:11][CH2:12][C:13](OCC)=[O:14])=O)(C)(C)C.Cl.C(N(CC)CC)C>O1CCOCC1>[N+:26]([C:23]1[CH:24]=[CH:25][C:20]([CH2:19][CH2:18][N:8]2[CH2:9][CH2:10][NH:11][CH2:12][C:13]2=[O:14])=[CH:21][CH:22]=1)([O-:28])=[O:27]To a solution of Ethyl [(2-{(tert-butoxycarbonyl) [2-(4-nitrophenyl)ethyl]amino}ethyl)amino]acetate (0.50 g, 1.3 mmol) in dioxane (4 mL) was added 4N HCl in dioxane (3.2 mL, 13 mmol). The solution was stirred at 25° C. for 2 hours. LC showed complete removal of the Boc group. The volatiles were removed under vacuum, and the residue was redissolved in toluene and ethanol. To that solution was added triethylamine (0.73 mL, 5.2 mmol). The mixture was heated to reflux for 48 hours. LC at that point showed mostly product. The product was purified by silica gel chromatography (DCM: MeOH) to afford 1-[2-(4-nitrophenyl)ethyl]piperazin-2-one. LC-MS (IE, m/z): 250 [M+1]+.
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