Reaction Steps
To a cooled (0° C.) suspension of N′-hydroxy-N-{5-[(2′-oxo-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-1′(2′H)-yl)methyl]pyridin-2-yl}imidoformamide (0.22 g, 0.5 mmol) in tetrahydrofuran (7 mL) was slowly added trifluoroacetic anhydride (0.08 mL, 0.54 mmol). The mixture was stirred at ambient temperature for 3 h, diluted with saturated aqueous sodium bicarbonate (10 mL) and extracted with ethyl acetate (3×50 mL). The combined organic layers was washed with saturated aqueous sodium bicarbonate (50 mL) and brine (50 mL), dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography and eluted with a 50% to 65% gradient of ethyl acetate in hexanes to afford 1′-([1,2,4]triazolo[1,5-a]pyridin-6-ylmethyl)-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.11 g, 54%) as a colorless solid: mp 207-209° C.; 1H NMR (300 MHz, DMSO-d6) δ8.65 (s, 1H), 8.37 (s, 1H), 7.82-7.77 (m, 1H), 7.61-7.55 (m, 1H), 7.30-7.17 (m, 2H), 7.11-7.04 (m, 1H), 6.90-6.85 (m, 1H), 6.52 (s, 1H), 6.18 (s, 1H), 5.03 (ABq, J=40.9, 15.6 Hz, 2H), 4.80 (ABq, J=79.6, 9.0 Hz, 2H), 4.23-4.09 (m, 4H); 13C NMR (75 MHz, DMSO-d6) δ 177.7, 155.2, 154.2, 149.9, 144.8, 141.2, 138.4, 132.1, 129.8, 129.0, 127.0, 124.4, 124.0, 123.0, 120.5, 117.4, 111.4, 108.6, 99.5, 80.0, 64.5, 63.9, 58.0, 41.2; MS (ES+) m/z 426.9 (M+1).
