Reaction Steps
Under an argon atmosphere, to a solution of 5-[4-(tert-butyldimethylsilyloxy)phenyl]-3-(phenylethynyl)pyrazin-2-amine (7p) (400 mg, 996 μmol) in ethyl acetate (20 mL) was added Palladium/charcoal activated (10% Pd) (80.0 mg) at room temperature. The atmosphere in the reaction flask was replaced with hydrogen gas and the mixture was stirred at room temperature for 3 hours. After replacing the atmosphere of the reaction system again with argon, to the mixture was added dichloromethane (15 mL) and stirred at room temperature for an hour. The catalyst was removed by filtration. After concentration under reduced pressure, the residue was purified by column chromatography (silica gel 40 g, n-hexane/ethyl acetate=2/1) to give Compound 7r (403 mg, 994 μmol, 99.8%) as a brown oily substance. Rf=0.48 (n-hexane/ethyl acetate=2/1); 1H NMR (400 MHz, DMSO-d6) δ 0.18 (s, 6H), 0.93 (s, 9H), 2.92 (t, 3H, J=8.0 Hz), 3.05 (t, 3H, J=8.0 Hz), 6.25 (s, 2H), 6.81-6.90 (AA′BB′, 2H), 7.10-7.18 (m, 1H), 7.18-7.35 (m, 4H), 7.75-7.85 (AA′BB′, 2H), 8.27 (s, 1H); 13C NMR (67.8 MHz, DMSO-d6) δ −4.5 (2C), 18.0, 25.6 (3C), 31.7, 34.0, 120.0 (2C), 125.7, 126.1 (2C), 128.2 (2C), 128.5 (2C), 130.9, 135.6, 138.5, 140.1, 141.9, 152.3, 154.6; IR (KBr, cm−1) 507, 635, 677, 698, 750, 781, 841, 914, 1009, 1103, 1146, 1167, 1213, 1254, 1389, 1420, 1454, 1512, 1605, 2857, 2928, 2955, 3061, 3318.
