Reaction Steps
To a stirred solution of 5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one (0.28 g, 1.0 mmol) in dry N,N-dimethylformamide (6 mL) was added cesium carbonate (2.30 g, 7.1 mmol) at ambient temperature. The mixture was stirred at ambient temperature for 30 min, and 5-(chloromethyl)-2-methoxypyrimidine (0.34 g, 2.1 mmol) in dry N,N-dimethylformamide (3 mL) was added dropwise. The mixture was stirred at ambient temperature for 16 h, and additional cesium carbonate (0.68 g, 2.1 mmol) and 5-(chloromethyl)-2-methoxypyrimidine (0.20 g, 1.3 mmol) were added. The mixture was stirred at ambient temperature for 64 h. Water (60 mL) was added and the mixture was extracted with ethyl acetate (3×60 mL). The combined organic solution was washed with brine (100 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The residue was purified by column chromatography (hexanes/ethyl acetate 1:1) to afford 1′-[(2-methoxypyrimidin-5-yl)methyl]-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one (0.29 g, 73%) as a colorless solid: mp 203-204° C.; 1H NMR (300 MHz, CDCl3) δ8.57 (s, 2H), 7.30-7.23 (m, 1H), 7.22-7.17 (m, 1H), 7.11-7.04 (m, 1H), 6.86-6.81 (m, 1H), 6.44-6.41 (m, 2H), 4.89 (ABq, 2H), 4.81 (ABq, 2H), 4.59-4.50 (m, 2H), 4.01 (s, 3H), 3.10-2.90 (m, 2H); 13C NMR (75 MHz, CDCl3) δ177.9, 165.4, 161.9, 161.3, 158.8, 141.1, 132.7, 128.8, 124.3, 123.9, 122.8, 120.1, 119.7, 118.7, 108.5, 93.3, 80.5, 72.4, 57.6, 55.1, 38.8, 29.0; MS (ES+) m/z 402.1 (M+1).
