Reaction Steps
To a solution of 4′-amino-1′-methyl-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (700 mg, 1.72 mmol) in dichloromethane (50 mL) and pyridine (5 mL) was added cyclobutanecarbonyl chloride (0.17 mL, 1.48 mmol) at 0° C. The reaction mixture was stirred at ambient temperature for 18 h, diluted with dichloromethane (150 mL), washed sequentially with water, 10% w/v hydrochloric acid, water and brine, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated in vacuo. The residue was subjected to column chromatography and eluted with ethyl acetate/hexanes (1/3) to afford N-(1′-methyl-2′-oxo-1′,2,2′,3-tetrahydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-4′-yl)cyclobutanecarboxamide (0.50 g, 71%): mp 234-236° C. (ethyl acetate/hexanes); 1H NMR (300 MHz, DMSO-d6) δ 8.15 (s, 1H), 7.32-7.26 (m, 1H), 7.11-7.08 (m, 1H), 6.94-6.91 (m, 1H), 6.43 (s, 1H), 6.17 (s, 1H), 4.68 (ABq, 2H), 4.13-4.05 (m, 4H), 3.15 (s, 3H), 2.96-2.90 (m, 1H), 2.05-1.64 (m, 6H); 13C NMR (75 MHz, DMSO-d6) δ 176.6, 173.5, 155.1, 144.6, 144.3, 138.3, 134.6, 129.5, 125.3, 120.8, 119.4, 112.0, 106.8, 98.8, 78.2, 64.6, 64.0, 57.1, 27.1, 25.0, 24.9, 17.9; MS (ES+) m/z 406.9 (M+1).
