Sulfuric Acid → 6-fluoro-1H-indazole-3-carboxylic Acid

HRID 2051179Notes

Reaction equation

HRID 2051179 reaction equation
[F:1][C:2]1[CH:10]=[C:9]2[C:5]([C:6](=O)[C:7](=[O:11])[NH:8]2)=[CH:4][CH:3]=1.[OH-:13].[Na+].[N:15]([O-])=O.[Na+].S(=O)(=O)(O)O>O.Cl>[F:1][C:2]1[CH:10]=[C:9]2[C:5]([C:6]([C:7]([OH:11])=[O:13])=[N:15][NH:8]2)=[CH:4][CH:3]=1

Participants

7

Reactant 4

HCID 1118Sulfuric AcidHCID 14798Sodium HydroxideHCID 3739056-FluoroisatinHCID 23668193Sodium Nitrite

Product 1

HCID 108212286-fluoro-1H-indazole-3-carboxylic Acid

Reagents, catalysts & solvents 2

HCID 313Hydrochloric AcidSolventHCID 962WaterSolvent3×

Conditions

Temperature
0 °C

Procedure

6-Fluoroisatin prepared according to the method of J. Org. Chem., 21, 169 (1956) is added to a solution of sodium hydroxide (7.4 g) in water (130 ml), and the mixture obtained is gently heated until it dissolves. After the solution is cooled to 0° C., a solution of sodium nitrite (13.8 g) in water (45 ml) is added dropwise to the reaction mixture, and this mixture is poured, in small portions with vigorous stirring, into the sulfuric acid (33.9 g) in water (430 ml) at 0° C. The mixture is stirred for 30 minutes at 0° C. A solution of stannous chloride (85.3 g) in hydrochloric acid (170 ml) is added dropwise to the reaction mixture at 0° C., and the mixture is stirred at 25° C. for 2 hours. The precipitates are collected and washed successively with water, acetone, and methanol, and dried to give the title compound (15.6 g), m.p. > 290° C. Mass spectrum: m/z 180.

Workup

  1. customthe mixture obtained
  2. temperatureis gently heated until it
  3. dissolutiondissolves
  4. stirringthe mixture is stirred at 25° C. for 2 hours
  5. customThe precipitates are collected
  6. washwashed successively with water, acetone, and methanol
  7. customdried

Sources & evidence

ORD record
ord-ea9dc9ddeeef4f17849ab93dc0836799
Source dataset
uspto-grants-1991_05
Patent number
US05017573

Reaction notes

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