Reaction Steps
To a suspended mixture of 4′-bromospiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (1.00 g, 2.78 mmol), 6-(dimethylamino)pyridin-3-ylboronic acid (0.69 g, 4.17 mmol) and tetrakis(triphenylphosphine)palladium (0) (0.32 g, 0.28 mmol) in N,N-dimethylformamide (30 mL) was added aqueous 2 M sodium carbonate (2.8 mL, 5.6 mmol). The reaction mixture was refluxed for 3 h. The solid was filtered and washed with ethyl acetate (40 mL). The filtrate was concentrated in vacuo to dryness. The residue was purified by column chromatography with ethyl acetate in hexanes (20% to 50% gradient) to afford 4′-[6-(dimethylamino)pyridin-3-yl]spiro[furo[2,3-f][1,3]benzodioxole-7,3′-indol]-2′(1′H)-one (0.60 g, 54%) as a white powder: mp>245° C. (ethyl acetate); 1H NMR (300 MHz, DMSO-d6) δ10.69 (s, 1H), 7.59 (d, J=2.4 Hz, 1H), 7.29 (dd, J=7.8, 7.8 Hz, 1H), 6.93 (d, J=7.8 Hz, 1H), 6.79-6.74 (m, 2H), 6.40-6.35 (m, 3H), 5.95 (d, J=19.9 Hz, 2H), 4.52 (d, J=9.3 Hz, 1H), 4.36 (d, J=9.3 Hz, 1H), 2.99 (s, 6H); 13C NMR (75 MHz, DMSO-d6) δ 178.8, 157.9, 155.5, 148.1, 146.6, 142.2, 141.5, 137.0, 136.8, 129.8, 128.9, 124.4, 121.9, 121.2, 109.0, 104.2, 102.5, 101.3, 93.1, 77.5, 58.2, 37.6; MS (ES+) m/z 402.3 (M+1).
