Hydrochloric Acid → 5-Methoxyoxindole

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-methoxyisatin (10.62 g, 60 mmol) in DMSO (30 mL) was added N2H4.xH2O (hydrazine hydrate, 6 mL, 120 mmol) dropwise over 5 min (exothermic). After addition, the resulting mixture was heated at 140° C. (oil temp.) for 2 h and then cooled to rt. After diluting with H2O (30 mL), 6 M HCl (12 mL, 72 mmol) was added and the resulting mixture was stirred for 1 h at rt. Ice (30 mL) was added and the reaction mixture was stirred O/N at rt. The precipitate formed was collected by suction filtration, rinsed with H2O, then dried to give the 5-methoxyoxindole (6.523 g) as a brown solid. (about 10% impurity being the oxime from starting material 5-methoxyisatin) 1H NMR (400 MHz, d6-DMSO) 6.78 (s, 1H), 6.85 (s, 1H), 6.72-6.79 (m, 2H), 3.39 (s, 3H); ESI 164.0 [M+H]+, calcd for [C9H9NO2+H]+ 164.1.

Provenance & Evidence