To a cooled (0° C.) solution of 1′-[(6-oxo-1,6-dihydropyridin-3-yl)methyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.07 g, 0.17 mmol) in anhydrous N,N-dimethylformamide (3 mL) was added sodium hydride (60% in mineral oil, 0.01 g, 0.25 mmol). The mixture was stirred at ambient temperature for 1 h, and iodomethane (0.02 mL, 0.27 mmol) was added. The mixture was stirred at ambient temperature for 16 h, diluted with water (15 mL) and extracted with ethyl acetate (3×30 mL). The combined organic layers was washed with brine (35 mL), dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography and eluted with a 10% to 30% gradient of acetone in dichloromethane to afford 1′-[(1-methyl-6-oxo-1,6-dihydropyridin-3-yl)methyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.03 g, 42%) as a colorless solid: mp 205-207° C.; 1H NMR (300 MHz, CDCl3) δ7.40-7.34 (m, 2H), 7.33-7.26 (m, 1H), 7.21-7.16 (m, 1H), 7.11-7.04 (m, 1H), 6.91-6.85 (m, 1H), 6.60-6.54 (m, 1H), 6.50 (s, 1H), 6.12 (s, 1H), 4.77 (ABq, J=75.6, 9.0 Hz, 2H), 4.66 (ABq, J=58.2, 15.3 Hz, 2H), 4.22-4.08 (m, 4H), 3.53 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 177.7, 162.5, 155.2, 144.7, 141.5, 139.6, 138.3, 137.4, 132.2, 128.9, 124.3, 123.8, 121.3, 120.7, 114.0, 111.2, 108.5, 99.5, 79.8, 64.5, 63.9, 57.9, 40.8, 37.9; MS (ES+) m/z 416.9 (M+1).
