Sulfuric Acid → 5-fluoro-1H-indazole-3-carboxylic acid
Reaction equation
[F:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[NH:7][C:6](=[O:11])[C:5]2=O.[OH-:13].[Na+].[N:15]([O-])=O.[Na+].S(=O)(=O)(O)O.[Sn](Cl)Cl>O.Cl>[F:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[NH:7][N:15]=[C:5]2[C:6]([OH:11])=[O:13]Participants
Conditions
- Temperature
- 5 °C
Procedure
A solution of 5-fluoroisatin (2 g) and sodium hydroxide (0.509 g) in water (20 ml) was heated to 50° C. for 30 minutes, then cooled and then treated with sodium nitrite (0.836 g). This mixture was added over 10 minutes to a solution of concentrated sulfuric acid (2.26 g) in water (200 ml), at 0° C., whilst maintaining the temperature below 5° C. After a further 15 minutes a solution of tin (II) chloride (5.51 g) in concentrated hydrochloric acid (10.5 ml) was added and the resulting mixture maintained at 5° C. for a further 30 minutes. The mixture was then stirred for a further 1 hour whilst warming to ambient temperature then filtered. The light brown paste was dissolved in ethyl acetate and the solution was dried over magnesium sulfate and then evaporated to yield 5-fluoro-1H-indazole-3-carboxylic acid (0.863 g) as a light brown solid which was used without further purification.
Workup
- temperaturecooled
- temperaturewhilst maintaining the temperature below 5° C
- temperaturewhilst warming to ambient temperature
- filtrationthen filtered
- dissolutionThe light brown paste was dissolved in ethyl acetate
- dry with materialthe solution was dried over magnesium sulfate
- customevaporated
Sources & evidence
- ORD record
- ord-127cb5209a214d81b97879f6644a755d
- Source dataset
- uspto-grants-2012_10
- Patent number
- US08288425B2
Reaction notes
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