Reaction Steps
A solution of 3-[(2′-oxo-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-1′(2′H)-yl)methyl]benzamide (0.50 g, 1.17 mmol) and N,N-dimethylacetamide dimethyl acetal (0.60 mL, 4.1 mmol) in 1,4-dioxane (10 mL) was stirred at 110° C. for 3 h, allowed to cool to ambient temperature and concentrated in vacuo. Hydroxylamine hydrochloride (0.11 g, 1.6 mmol), 1,4-dioxane (10 mL), glacial acetic acid (10 mL) and 2 M aqueous sodium hydroxide (0.85 mL, 1.70 mmol) were then added and the mixture was heated at 90° C. for 2 h. The mixture was allowed to cool to ambient temperature and water was added, causing a precipitate to be deposited. The solid was collected by filtration, washed with water and hexanes and recrystallized from dichloromethane/hexanes to afford 1′-[3-(3-methyl-1,2,4-oxadiazol-5-yl)benzyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.038 g, 6%) as a colorless solid: mp 80-89° C. (dichloromethane/hexanes); 1H NMR (300 MHz, CDCl3) δ 8.09-8.12 (m, 2H), 7.54-7.57 (m, 2H), 7.15-7.18 (m, 2H), 7.00-7.03 (m, 1H), 6.74-6.77 (m, 1H), 6.50 (s, 1H), 6.29 (s, 1H), 5.14-5.17 (m, 1H), 4.89-4.92 (m, 2H), 4.65-4.67 (m, 1H), 4.13-4.17 (m, 4H), 2.43 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 177.6, 174.9, 167.9, 155.3, 144.7, 141.7, 138.4, 137.0, 132.3, 131.4, 129.9, 128.9, 127.4, 126.8, 124.8, 124.1, 123.7, 120.8, 111.6, 109.1, 99.5, 80.2, 64.5, 63.9, 58.1, 43.7, 11.7; MS (ES+) m/z 467.8 (M+1).
