Trifluoroacetic acid → 1-Methyl-4-nitro-2,3-dihydro-1H-indole

HRID 230859Notes

Reaction equation

HRID 230859 reaction equation
[CH3:1][N:2]1[C:10]2[C:5](=[C:6]([N+:11]([O-:13])=[O:12])[CH:7]=[CH:8][CH:9]=2)[CH:4]=[CH:3]1.B.O1CCCC1.FC(F)(F)C(O)=O>C(=O)([O-])[O-].[Na+].[Na+]>[CH3:1][N:2]1[C:10]2[C:5](=[C:6]([N+:11]([O-:13])=[O:12])[CH:7]=[CH:8][CH:9]=2)[CH2:4][CH2:3]1

Participants

5

Reactant 3

HCID 6422Trifluoroacetic acidHCID 2723981Borane;tetrahydrofuranHCID 131680671-Methyl-4-nitro-1H-indole

Product 1

HCID 577631791-Methyl-4-nitro-2,3-dihydro-1H-indoleYield 51.3%

Reagents, catalysts & solvents 1

HCID 10340Sodium CarbonateSolvent

Procedure

To a stirred solution of 1-methyl-4-nitro-1H-indole (3.8 g, Organic Process Research and Development 2001 5 (6) 604) and borane-tetrahydrofuran complex (1M in tetrahydrofuran, 86.3 ml) at 0° C. under an atmosphere of nitrogen was added, dropwise, trifluoroacetic acid (88 ml). The resulting mixture was allowed to warm to room temperature and stirred at room temperature for 90 min. The mixture was cautiously added to 2M sodium carbonate solution (750 ml) over 20 min and then stirred for 30 min. The mixture was extracted with ethyl acetate (2×300 ml), the combined organic extracts were dried over sodium sulphate and the solvent was removed in vacuo. Purification by column chromatography on silica gel, eluting with hexane : ethyl acetate (9:1) gave the title compound as a red solid (1.97 g).

Workup

  1. stirringstirred for 30 min
  2. extractionThe mixture was extracted with ethyl acetate (2×300 ml)
  3. dry with materialthe combined organic extracts were dried over sodium sulphate
  4. customthe solvent was removed in vacuo
  5. customPurification by column chromatography on silica gel
  6. washeluting with hexane : ethyl acetate (9:1)

Sources & evidence

ORD record
ord-e34d687d09d9409286f47cc138549578
Source dataset
uspto-grants-2009_07
Patent number
US07566786B2

Reaction notes

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