Triethylsilane → 4'-fluoro-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3'-indol]-2'(1'H)-one

Participants

Reaction Steps

A solution of 1′-(diphenylmethyl)-4′-fluoro-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (1.18 g, 2.45 mmol) and triethylsilane (1.21 g, 9.84 mmol) in trifluoroacetic acid (20 mL) was heated at 65° C. for 16 h. After cooling to ambient temperature, the reaction mixture was concentrated in vacuo. The residue was recrystallized from N,N′-dimethylformamide/water to afford 4′-fluoro-2,3-dihydrospiro[furo[2,3-g][1,4]benzodioxine-8,3′-indol]-2′(1′H)-one (0.65 g, 84%) as a colourless solid: mp 282-285° C.; 1H NMR (300 MHz, DMSO-d6) δ 10.83 (s, 1H), 7.30 (ddd, J=8.2, 8.2, 5.9 Hz, 1H), 6.78 (d, J=8.0 Hz, 1H), 6.75 (d, J=9.2 Hz, 1H), 6.47 (s, 1H), 6.27 (s, 1H), 4.71 (dd, J=9.4 Hz, 2H), 4.14 (dd, J=5.3, 3.2 Hz, 4H); 13C NMR (75 MHz, DMSO-d6) δ 176.3, 160.9 (d, 1JC-F=244 Hz), 147.0, 143.3 (d, 2JC-F=96.3 Hz), 135.5, 131.9, 131.2 (d, 4JC-F=2.9 Hz), 128.6, 128.5, 123.2 (d, 2JC-F=120 Hz), 116.4 (d, 3JC-F=22.8 Hz), 115.1, 108.2, 103.3, 74.3, 64.2, 63.7; MS (ES+) m/z 313.1 (M+1).

Provenance & Evidence