Reaction Steps
A mixture of spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (1.05 g, 3.73 mmol), 4-bromobenzyl bromide (1.21 g, 4.84 mmol) and cesium carbonate (1.84 g, 5.65 mmol) in 2-butanone (25 mL) was stirred at ambient temperature for 16 h. The mixture was diluted with ethyl acetate and filtered through Celite. The filtrate was concentrated to dryness under reduced pressure. The residue was purified by flash column chromatography with hexanes/ethyl acetate (9:1, increased to 1:1) to afford 1′-(4-bromobenzyl)spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (1.42 g, 84%) as a colorless solid: mp 148-150° C. (hexanes); 1H NMR (300 MHz, CDCl3) δ7.48 (d, J=8.4 Hz, 2H), 7.25-7.17 (m, 4H), 7.05 (dd, J=7.5, 7.5 Hz, 1H), 6.77 (d, J=7.8 Hz, 1H), 6.53 (s, 1H), 6.12 (s, 1H), 5.89 (s, 1H), 5.88 (s, 1H), 5.02 (d, J=15.6 Hz, 1H), 4.97 (d, J=9.0 Hz, 1H), 4.78 (d, J=15.6 Hz, 1H), 4.70 (d, J=9.0 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ177.8, 156.1, 149.1, 142.5, 141.9, 134.9, 132.3, 132.2, 129.3, 129.1, 124.2, 123.8, 122.0, 119.4, 109.3, 103.1, 101.7, 93.8, 80.6, 58.4, 43.7; MS (ES+) m/z 452.0 (M+1), 450.0 (M+1).
