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To an oven-dried flask, 1-boc-piperazine (1.59 g, 8.5 mmol), Cs2CO3 (2.91 g, 8.93 mmol), Pd2(dba)3 (0.72 g, 0.78 mmol), rac-2,2′bis(diphenylphosphino)-1,1′-binaphthyl (0.44 g, 0.71 mmol), toluene (6 mL) and compound 24 (1.76 g, 7.14 mmol) were added. While stirring the reaction mixture at room temperature, the air in the flask was removed and replaced by N2. This process was repeated three times. The reaction mixture was further stirred at room temperature for 0.5 h. Ethyl acetate (50 mL) was added to the mixture at room temperature, washed with H2O (15 mL) and brine (10 mL), dried over Na2SO4, and evaporated. The brown oily material was chromatographed on a silica column, eluting with hexanes:ethyl acetate (30:70), and then changing to (40:60), yielding compound 25. Yield: 78%, yellow solid. IR (KBr, cm−1) 3073 (Ar—H), 1683 (CO), 1528, 1432 (C═C), 1226 (C—N), 1151 (C-0); 1H NMR (500 MHz, CDCl3) δ 1.48 (9H, s, OC(CH3)3), 3.02 (m, 4H, 2CH2), 3.58 (m, 4H, 2CH2), 7.17 (dd, J=2.6, 8.8 Hz, 1H, H-6), 7.24 (d, J=2.5 Hz, 1H, H-2), 7.71 (d, J=8.5 Hz, 1H, H-4). 13C NMR (125.7 MHz, CDCl3) δ 28.30 (OC(CH3)3), 48.24 (CH2), 51.39 (CH2), 80.12 (OC(CH3)3), 124.23 (C-2), 124.92 (C-6), 127.49 (C-5), 128.17 (C-4), 141.62 (C-3), 146.94 (C-1), 154.60 (CO). Anal. Calcd for C15H20N4O6: C, 51.13; 11, 5.72; N, 15.90%. Found: C, 51.07; H, 5.78; N, 15.82%.
