Sulfuric Acid → 4-chloro-5-fluoro-1H-indole-2,3-dione

HRID 245136

Reaction equation

HRID 245136 reaction equation
[Cl:1][C:2]1[CH:3]=[C:4]([NH:9][C:10](=[O:14])[CH:11]=NO)[CH:5]=[CH:6][C:7]=1[F:8].[OH:15]S(O)(=O)=O>>[Cl:1][C:2]1[CH:3]=[C:4]2[C:5]([C:11](=[O:15])[C:10](=[O:14])[NH:9]2)=[CH:6][C:7]=1[F:8].[Cl:1][C:2]1[C:7]([F:8])=[CH:6][CH:5]=[C:4]2[C:3]=1[C:11](=[O:15])[C:10](=[O:14])[NH:9]2

Participants

4

Reactant 2

HCID 1118Sulfuric AcidHCID 73843641N-(3-chloro-4-fluorophenyl)-2-(hydroxyimino)ethanamide

Product 2

HCID 149861234-chloro-5-fluoro-1H-indole-2,3-dioneHCID 217955255-Fluoro-6-chloroisatin

Conditions

Temperature
90 °C

Procedure

To concentrated H2SO4 (100 ml) at 65° C. was added N-(3-chloro-4-fluorophenyl)-2-(hydroxyimino)ethanamide (19.45 g, 90 mmol) portionwise. The mixture was heated at 90° C. for 1.5 h. The mixture was cooled to room temperature, poured onto ice, and stirred for 10 min. The solid was collected by filtration, washed with water, and air dried to afford 6-chloro-5-fluoro-1H-indole-2,3-dione and 4-chloro-5-fluoro-1H-indole-2,3-dione as a mixture of regioisomers (15.5 g, 86% yield). This material was used without further purification.

Workup

  1. temperatureThe mixture was cooled to room temperature
  2. additionpoured onto ice
  3. filtrationThe solid was collected by filtration
  4. washwashed with water, and air
  5. customdried

Sources & evidence

ORD record
ord-e69cad0a06c648e38b823054c26ef33f
Source dataset
uspto-grants-2014_02
Patent number
US08658636B2

Linked notes

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