A 50 mL round-bottom flask was charged with 2-[(2′-oxo-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-1′(2′H)-yl)methyl]pyridine-3-carboxylic acid (0.43 g, 1.0 mmol), methylamine hydrochloride (0.14 g, 2.0 mmol), 1-ethyl-3-(3-dimethyllaminopropyl)carbodiimide hydrochloride (0.26 g, 1.4 mmol), 1-hydroxybenzotriazole (0.20 g, 1.5 mmol), N-methylmorpholine (0.4 mL, 3.6 mmol) and N,N-dimethylformamide (7 mL). The reaction mixture was stirred under nitrogen at ambient temperature for 20 h, and poured into water (200 mL). The solid was collected by filtration, washed with water, dried and purified by column chromatography and eluted with a 0% to 50% gradient of ethyl acetate in dichloromethane to afford N-methyl-2-[(2′-oxo-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-1′(2′H)-yl)methyl]pyridine-3-carboxamide (0.41 g, 92%) as an off-white solid: 1H NMR (300 MHz, CDCl3) δ 8.43 (d, J=4.8 Hz, 1H), 7.85 (d, J=7.7 Hz, 1H), 7.36 (dd, J=7.5, 5.0 Hz, 1H), 7.20-7.07 (m, 2H), 6.95 (t, J=7.5, 1H), 6.81 (d, J=7.8 Hz, 1H), 6.46 (d, J=1.2 Hz, 1H), 6.43 (d, J=1.2 Hz, 1H), 5.16 (ABq, 2H), 4.70 (ABq, 2H), 4.20-4.05 (m, 4H), 2.77 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 177.3, 167.6, 154.9, 152.7, 150.1, 144.5, 143.3, 138.1, 136.2, 132.5, 131.6, 129.0, 123.7, 123.1, 122.9, 122.2, 112.4, 109.6, 99.0, 79.7, 64.6, 64.1, 57.7, 43.3, 26.5; MS (ES+) m/z 443.9 (M+1).
