Sodium hydride → 1'-[4-(benzyloxy)benzyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3'-indol]-2'(1'H)-one

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Reaction Steps

To a solution of 2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (2.0 g, 6.8 mmol) in dry N,N-dimethylformamide (45 mL) was added sodium hydride (60% in mineral oil, 0.35 g, 8.8 mmol) at ambient temperature. The mixture was stirred at ambient temperature for 1 h and 4-benzyloxybenzyl chloride (2.2 g, 9.4 mmol) was added in one portion, followed by potassium iodide (0.06 g, 0.34 mmol). The mixture was stirred at ambient temperature for 16 h and diluted with water (200 mL) and ethyl acetate (200 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate (2×100 mL). The combined organic layers were washed with brine (150 mL), dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography and eluted with a 25% to 35% gradient of ethyl acetate in hexanes to afford 1′-[4-(benzyloxy)benzyl]-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (2.49 g, 75%) as a colorless solid: mp 87-89° C.; 1H NMR (300 MHz, CDCl3) δ 7.45-7.24 (m, 7H), 7.24-7.12 (m, 2H), 7.05-6.92 (m, 3H), 6.84-6.79 (m, 1H), 6.51 (s, 1H), 6.22 (s, 1H), 5.06-4.90 (m, 4H), 4.82-4.62 (m, 2H), 4.24-4.08 (m, 4H); 13C NMR (75 MHz, CDCl3) δ 177.4, 158.4, 155.2, 144.6, 142.1, 138.3, 136.8, 132.3, 128.7 (2C), 128.6, 128.0 (2C), 127.5, 123.8, 123.3, 121.0, 115.2, 111.5, 109.3, 99.4, 80.2, 70.0, 64.5, 63.9, 58.0, 43.6; MS (ES+) m/z 492.0 (M+1).

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