Reaction Steps
To a solution of (8S)-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.40 g, 1.35 mmol) in 2-butanone (15 mL) was added cesium carbonate (1.76 g, 5.40 mmol), 3-(chloromethyl)-5-fluoropyridine hydrochloride (0.49 g, 2.69 mmol) and potassium iodide (0.085 g, 38 mol %). This mixture was stirred under nitrogen at ambient temperature for 72 h. Further, cesium carbonate (1.76 g, 5.40 mmol), 3-(chloromethyl)-5-fluoropyridine hydrochloride (0.49 g, 2.69 mmol) and tetra-n-butylammonium iodide (0.08 g, 0.22 mmol) were added and the reaction mixture was heated at reflux for 48 h, allowed to cool to ambient temperature, filtered and concentrated in vacuo. The residue was purified by column chromatography and eluted with a 10% to 40% gradient of ethyl acetate in hexanes and recrystallized from diethyl ether to afford (8S)-1′-[(5-fluoropyridin-3-yl)methyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (102.1 mg, 19%) as a yellow solid: mp 197-200° C. (diethyl ether); 1H NMR (300 MHz, CDCl3) δ 8.48-8.42 (m, 2H), 7.40-7.37 (m, 1H), 7.26-7.17 (m, 2H), 7.08-7.03 (m, 1H), 6.78-6.76 (m, 1H), 6.50 (s, 1H), 6.18 (s, 1H), 5.06-4.88 (m, 3H), 4.66-4.63 (m, 1H), 4.20-4.09 (m, 4H); 13C NMR (75 MHz, CDCl3) δ 177.7, 155.3, 144.8, 144.4, 141.3, 138.4, 138.0, 137.7, 132.1, 129.0, 124.3, 124.0, 122.4, 122.2, 120.5, 111.4, 108.7, 99.5, 80.1, 64.5, 63.9, 58.0, 41.1; MS (ES+) m/z 404.9 (M+1).
