Reaction Steps
To a solution of ethyl {4-[(2′-oxo-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-1′(2′H)-yl)methyl]phenoxy}acetate (0.22 g, 0.44 mmol) in anhydrous 1,2-dimethoxyethane (5 mL) was added at 0° C. lithium borohydride (2.0 M solution in tetrahydrofuran, 0.44 mL, 0.88 mmol) dropwise. The mixture was stirred at ambient temperature for 2 h, cooled to 0° C., and 7% w/v aqueous citric acid (15 mL) was added dropwise. The mixture was extracted with chloroform (3×60 mL). The combined organic layers was washed with saturated aqueous sodium bicarbonate (50 mL) and brine (50 mL), dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography eluted with 50% ethyl acetate in hexanes to afford 1′-[4-(2-hydroxyethoxy)benzyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.12 g, 63%) as a colorless solid: mp 196-197° C.; 1H NMR (300 MHz, CDCl3) δ 7.31-7.24 (m, 2H), 7.23-7.12 (m, 2H), 7.05-6.97 (m, 1H), 6.92-6.86 (m, 2H), 6.83-6.78 (m, 1H), 6.51 (s, 1H), 6.22 (s, 1H), 4.89 (ABq, J=79.6, 15.4 Hz, 2H), 4.79 (ABq, J=83.8, 8.9 Hz, 2H), 4.22-4.08 (m, 4H), 4.08-3.91 (m, 4H), 1.94 (s, 1H); 13C NMR (300 MHz, CDCl3) δ 177.5, 158.2, 155.2, 144.6, 142.0, 138.2, 132.3, 128.8, 128.7, 128.2, 123.8, 123.3, 121.0, 114.9, 111.5, 109.3, 99.4, 80.1, 69.1, 64.5, 63.9, 61.4, 58.0, 43.6; MS (ES+) m/z 446.0 (M+1).
