Reaction Steps
To a solution of 1-(diphenylmethyl)-4-fluoro-3-hydroxy-3-(7-hydroxy-2,3-dihydro-1,4-benzodioxin-6-yl)-1,3-dihydro-2H-indol-2-one (1.74 g, 3.60 mmol) in dichloromethane (40 mL) was added trifluoroacetic acid (1.64 g, 14.4 mmol) and triethylsilane (1.68 g, 14.4 mL). The reaction mixture was stirred at ambient temperature for 16 h and concentrated in vacuo. The residue was purified by column chromatography and eluted with a gradient of ethyl acetate in hexanes to afford 1-(diphenylmethyl)-4-fluoro-3-(7-hydroxy-2,3-dihydro-1,4-benzodioxin-6-yl)-1,3-dihydro-2H-indol-2-one (1.54 g, 92%) as a colourless solid: mp 115-118° C.; 1H NMR (300 MHz, DMSO-d6) δ 9.17 (s, 1H), 7.42-7.26 (m, 11H), 7.01 (ddd, J=8.2, 8.2, 5.9 Hz, 1H), 6.91 (s, 1H), 6.67 (dd, J=8.8, 8.8 Hz, 1H), 6.27 (s, 1H), 6.23 (d, J=7.9 Hz, 1H), 4.99 (s, 1H), 4.20-4.14 (m, 4H); 13C NMR (75 MHz, DMSO-d6) δ 176.2, 157.9 (d, 1JC-F=248 Hz), 147.1, 145.0 (d, 3JC-F=8.7 Hz), 142.7, 137.7 (d, 2JC-F=30.9 Hz), 135.4, 130.1 (d, 3JC-F=8.7 Hz), 128.4 (d, 3JC-F=13.9 Hz), 128.3 (d, 3JC-F=8.4 Hz), 127.5 (d, 3JC-F=11.9 Hz), 119.4, 117.9 (d, 2JC-F=18.9 Hz), 116.1, 109.3 (d, 2JC-F=20.3 Hz), 107.2 (d, 4JC-F=2.1 Hz), 103.1, 73.0, 64.2, 63.7, 57.5; MS (ES+) m/z 467.9 (M+1)
