Reaction Steps
To a stirred solution of 1′-(3-hydroxybenzyl)-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-2′(1′H)-one (0.46 g, 1.18 mmol) in N,N-dimethylformamide (4 mL) were added potassium carbonate (0.32 g, 2.36 mmol), ethyl bromoacetate (0.20 mL, 1.77 mmol), and potassium iodide (0.024 g, 0.14 mmol) at ambient temperature. The mixture was stirred at 40° C. for 16 h. Water (50 mL) and ethyl acetate (150 mL) were added to the mixture. The organic solution was separated and the aqueous layer was extracted with ethyl acetate (2×80 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 from 2:1 to 1:1) to afford ethyl {3-[(2′-oxo-5,6-dihydrospiro[benzo[1,2-b:5,4-b′]difuran-3,3′-indol]-1′(2′H)-yl)methyl]phenoxy}acetate (0.52 g, 93%): mp 45-46° C.; 1H NMR (300 MHz, CDCl3) δ 7.30-7.15 (m, 3H), 7.06-6.96 (m, 2H), 6.90 (br s, 1H), 6.84-6.76 (m, 2H), 6.50 (s, 1H), 6.43 (s, 1H), 5.07-4.96 (m, 2H), 4.87-4.78 (m, 1H), 4.75-4.68 (m, 1H), 4.60-4.50 (m, 4H), 4.22 (q, J=7.1 Hz, 2H), 3.11-2.91 (m, 2H), 1.26 (t, J=7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3) δ 177.9, 168.7, 161.8, 161.3, 158.2, 142.0, 137.6, 132.7, 130.0, 128.7, 123.8, 123.4, 120.7, 120.2, 119.9, 118.9, 114.0, 113.7, 109.2, 93.2, 80.6, 72.4, 65.4, 61.4, 57.7, 44.0, 29.0, 14.1; MS (ES+) m/z 471.9 (M+1).
