4-Methylindole → 4-Methylindoline

HRID 53151

Reaction equation

HRID 53151 reaction equation
[CH3:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH:4]=[CH:5][NH:6]2.[BH3-]C#N.[Na+]>C(O)(=O)C>[CH3:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH2:4][CH2:5][NH:6]2

Participants

4

Reactant 2

HCID 852824-MethylindoleHCID 5003444Sodium cyanoborohydride

Product 1

HCID 5837034-MethylindolineYield 92.2%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

To a solution of 4-methylindole (7.433 g, 0.0567 mol) in 100 mL of glacial acetic acid was added NaCNBH3 (7.25 g, 0.12 mol) portionwise over 1.5 h. The reaction mixture was then concentrated in vacuo water was added and the solution was basified with 10N NaOH. The resulting mixture was extracted with ethyl acetate (×3) and the organic extract was washed (brine), dried (Na2SO4) and evaporated to give an oil. Flash chromatography (SiO2 /ethyl acetate-hexane, 1:4) of this oil gave pure 4-methylindoline (6.962 g, 92%) as an oil: 1H NMR (DMSO-d6, 200 MHz) δ6.78 (t, J=7.6 Hz, 1H), 6.33 (d, J=7.4 Hz, 1H), 6.30 (d, J=7.6 Hz, 1H), 5.36 (br s, 1H), 3.38 (t, J=8.5 Hz, 2H), 2.81 (t, J=8.5 Hz, 2H), 2.11 (s, 3H).

Workup

  1. concentrationThe reaction mixture was then concentrated in vacuo water
  2. additionwas added
  3. extractionThe resulting mixture was extracted with ethyl acetate (×3)
  4. extractionthe organic extract
  5. washwas washed (brine)
  6. dry with materialdried (Na2SO4)
  7. customevaporated
  8. customto give an oil

Sources & evidence

ORD record
ord-018dd87bdd534d888b93dd1b102cb8bb
Source dataset
uspto-grants-1997_04
Patent number
US05618816

Linked notes

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