Hydrochloric Acid → 5-Methoxyoxindole

HRID 2281690Notes

Reaction equation

HRID 2281690 reaction equation
[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][C:7](=[O:12])[C:6]2=O.Cl>CS(C)=O.O>[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][C:7](=[O:12])[CH2:6]2

Participants

5

Reactant 2

HCID 313Hydrochloric AcidHCID 383335-Methoxyisatin

Product 1

HCID 15142865-MethoxyoxindoleYield 66.6%

Reagents, catalysts & solvents 2

HCID 679Dimethyl SulfoxideSolventHCID 962WaterSolvent2×

Conditions

Temperature
140 °C

Procedure

To a solution of 5-methoxyisatin (10.62 g, 60 mmol) in DMSO (30 mL) was added N2H4.×H2O (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.

Workup

  1. additionAfter addition
  2. temperaturecooled to rt
  3. additionwas added
  4. stirringthe reaction mixture was stirred O/N at rt
  5. customThe precipitate formed
  6. filtrationwas collected by suction filtration
  7. washrinsed with H2O
  8. customdried

Sources & evidence

ORD record
ord-80b6fc648e75476a8ecef48ed1e5f5c2
Source dataset
uspto-grants-2015_09
Patent number
US09139563B2

Reaction notes

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