Reaction Steps
To a solution of (8S)-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.27 g, 0.9 mmol) in dry N,N-dimethylformamide (15 mL) was added sodium hydride (60% w/w dispersion in mineral oil, 0.054 g, 1.4 mmol) at ambient temperature. The mixture was stirred at ambient temperature for 15 minutes and 1-bromo-2-(2-methoxyethoxy)ethane (0.33 g, 1.8 mmol) was added in one portion. The mixture was stirred at 60° C. for 6 h and concentrated in vacuo. Water (50 mL) was added to the residue and the mixture was extracted with ethyl acetate. The combined organic layers were dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography and eluted with 40% ethyl acetate in hexanes to afford (8S)-1′-[2-(2-methoxyethoxy)ethyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.31 g, 85%) as a colorless oil: 1H NMR (300 MHz, CDCl3) δ 7.32-7.20 (m, 1H), 7.15-7.08 (m, 1H), 7.05-6.96 (m, 2H), 6.46 (s, 1H), 6.21 (s, 1H), 4.73 (ABq, 2H), 4.20-4.04 (m, 4H), 4.05-3.83 (m, 2H), 3.80-3.69 (m, 2H), 3.64-3.56 (m, 2H), 3.51-3.44 (m, 2H), 3.32 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 177.5, 155.1, 144.5, 142.5, 138.2, 132.3, 128.6, 123.7, 123.2, 121.2, 111.5, 109.2, 99.3, 80.0, 71.9, 70.4, 68.1, 64.5, 63.9, 59.0, 57.9, 40.2; MS (ES+) m/z 397.9 (M+1).
