Trifluoroacetic acid → 7-[1-(diphenylmethyl)-2-oxo-2,3-dihydro-1H-indol-3-yl]-6-hydroxy-4-methyl-2H-1,4-benzoxazin-3(4H)-one

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Reaction Steps

To a solution of 7-[1-(diphenylmethyl)-3-hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl]-6-hydroxy-4-methyl-2H-1,4-benzoxazin-3(4H)-one (4.0 g, 8.1 mmol) in trifluoroacetic acid (1.8 mL, 24.4 mmol) was added triethylsilane (3.9 mL, 24.4 mmol) and the reaction mixture was stirred at ambient temperature for 16 h. The reaction mixture was concentrated in vacuo and the crude product was purified by column chromatography with ethyl acetate in hexanes (10 to 100% gradient) to afford 7-[1-(diphenylmethyl)-2-oxo-2,3-dihydro-1H-indol-3-yl]-6-hydroxy-4-methyl-2H-1,4-benzoxazin-3(4H)-one (2.66 g, 71%) as an off-white solid: 1H NMR (300 MHz, DMSO-d6) δ9.53 (s, 1H), 7.44-7.28 (m, 10H), 6.99-6.95 (m, 3H), 6.89-6.84 (m, 2H), 6.54 (s, 1H), 6.40 (m, 1H), 4.90 (s, 1H), 4.57 (s, 2H), 3.21 (s, 3H); MS (ES+) m/z 477.0 (M+1).

Provenance & Evidence