Sodium Dithionite → 4-fluoro-2-methyl-1H-indol-5-ol

HRID 984855Notes

Reaction equation

HRID 984855 reaction equation
[F:1][C:2]1[C:7]([OH:8])=[CH:6][CH:5]=[C:4]([N+:9]([O-])=O)[C:3]=1[CH2:12][C:13](=O)[CH3:14].S(S([O-])=O)([O-])=O.[Na+].[Na+]>O>[F:1][C:2]1[C:7]([OH:8])=[CH:6][CH:5]=[C:4]2[C:3]=1[CH:12]=[C:13]([CH3:14])[NH:9]2

Participants

4

Reactant 2

HCID 24489Sodium DithioniteHCID 223379951-(2-Fluoro-3-hydroxy-6-nitrophenyl)propan-2-one

Product 1

HCID 103520364-fluoro-2-methyl-1H-indol-5-olYield 81%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

1-(2-fluoro-3-hydroxy-6-nitrophenyl)-propan-2-one from previous step (50 g, 0.234 mol) was added to 2 liter round bottom flask. Water (1 L) was added, and the yellow suspension was stirred at RT. Sodium dithionite (225 g, 5.5 eq) was added in one portion and the reaction mixture was stirred and kept <30° C. until HPLC analysis indicated no starting material remained (typically less than 1 hour). Upon completion, the reaction mixture was cooled to 0° C. and the tan solid product was collected by vacuum filtration. The wet product was dried at <50° C. under house vacuum to afford 4-fluoro-2-methyl-1H-indol-5-ol (31.4 g, 81% yield) which was isolated as a tan crystalline powder. The material had an HPLC purity of >99.8. 1H NMR (CDCl3, 400 MHz) δ 7.8 (s, 1H), 6.9−6.7 (m, 2H), 6.2 (s, 1H), 4.7 (s, 1H), 2.4 (s, 3H).

Workup

  1. stirringthe reaction mixture was stirred
  2. customkept <30° C. until HPLC analysis
  3. customtypically less than 1 hour
  4. temperatureUpon completion, the reaction mixture was cooled to 0° C.
  5. filtrationthe tan solid product was collected by vacuum filtration
  6. customThe wet product was dried at <50° C. under house vacuum

Sources & evidence

ORD record
ord-2e8d506009154be5a253ef4d83070f58
Source dataset
uspto-grants-2005_03
Patent number
US06869952B2

Reaction notes

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