5-Bromoisatin → 5-Bromo-3-hydroxy-3-methyl-2-oxindole

Beteiligte Stoffe

Reaktionsschritte

A solution of 5-bromoisatin (5.0 g, 22 mmol) in dry THF (50 cm3) under N2 was cooled to 0° C. and treated drop-wise with methyl magnesium bromide (3M in diethylether, 14.7 cm3, 44 mmol) and the mixture was allowed to warm up-to room temperature. The reaction was poured into sat. ammonium chloride solution, then extracted into EtOAc (×3). The combined organic layers were then washed with water, brine, dried (MgSO4) and evaporated. The residue was then purified by column chromatography (SiO2, EtOAc: hexane, gradient elution) to afford 5-bromo-3-hydroxy-3-methyl-1,3-dihydro-indol-2-one (1.53 g, 6.32 mmol, 29%): 1H NMR (DMSO-d6) δ 1.38 (s, 3H), 5.99 (s, 1H), 6.77 (d, 1H, J=1.7 Hz), 7.38 (s, 1H, br); MS ((−) ESI) m/z 240/242 (M)−.

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