1-(Benzyloxycarbonyl)piperazine (117 μL, 134 mg, 0.607 mmol) was added to a mixture of N-[3-benzyloxy-4-(2-bromo-acetyl)phenyl]-acetamide (200 mg, 0.552 mmol) and potassium carbonate (115 mg, 0.828 mmol) in DMF (5 mL), and stirred at room temperature for 18 hours. The solvent was removed in vacuo, and taken up in brine (25 mL). The aqueous was extracted with DCM (3×25 mL) and the combined organics dried (MgSO4). The solvents were removed in vacuo, and the product was purified by preparative HPLC to give pure 4′-acetamido-2′-benzyloxy-2-[4-(benzyloxycarbonyl)piperazin-1-yl]acetophenone (114 mg, 41%, 50% rec.) as an off-white solid; δH (CDCl3) 8.23 (1H, br s), 7.81 (1H, d, J=8.6 Hz), 7.77-7.76 (1H, m), 7.53-7.51 (2H, m), 7.42-7.28 (8H, m), 7.08 (1H, dd, J=8.6, 1.8 Hz), 5.20 (2H, s), 5.12 (2H, s), 4.00 (2H, s), 3.59-3.48 (4H, m), 2.65-2.60 (4H, m), 2.14 (3H, s); LCMS retention time 2.07 min, M+H+ 502.5, along with recovered N-(4-acetyl-3-benzyloxy-phenyl)-acetamide (35 mg).
