Trifluoroacetic acid → 3-(7-Hydroxy-4-methyl-3,4-dihydro-2h-1,4-benzoxazin-6-yl)-1-{[5-(trifluoromethyl)furan-2-yl]methyl}-1,3-dihydro-2h-indol-2-one trifluoroacetate salt

Participants

Reaction Steps

To a cooled (0° C.) solution of triethylsilane (1.1 mL, 6.9 mmol) in trifluoroacetic acid (6.5 mL) was slowly added 3-hydroxy-3-(7-hydroxy-4-methyl-3,4-dihydro-2H-1,4-benzoxazin-6-yl)-1-{[5-(trifluoromethyl)furan-2-yl]methyl}-1,3-dihydro-2H-indol-2-one (1.00 g, 2.18 mmol) portionwise as a solid. The resulting brown solution was warmed to reflux and stirred under nitrogen for 2 h. The reaction was cooled and the solvent was removed under reduced pressure. The residue was precipitated from ethyl acetate/hexanes and collected by filtration to afford 3-(7-hydroxy-4-methyl-3,4-dihydro-2H-1,4-benzoxazin-6-yl)-1-{[5-(trifluoromethyl)furan-2-yl]methyl}-1,3-dihydro-2H-indol-2-one trifluoroacetate salt (1.09 g, 90%) as a light grey powder: mp 143-148° C. (hexanes); 1H NMR (300 MHz, DMSO-d6) δ8.98 (br s, 2H), 7.24-7.15 (m, 2H), 7.05-6.92 (m, 3H), 6.62 (s, 1H), 6.61 (s, 1H), 6.22 (s, 1H), 5.08 (d, J=16.7 Hz, 1H), 5.01 (d, J=16.7 Hz, 1H), 4.78 (s, 1H), 4.27-4.21 (m, 2H), 3.23-3.17 (m, 2H), 2.77 (s, 3H); MS (ES+) m/z 445.2 (M+1).

Provenance & Evidence