4-Methylindole → 4-Methylindoline

HRID 441092

Reaction equation

HRID 441092 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) δ 6.78 (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-7053962630f64b87922abe59ece4e47e
Source dataset
uspto-grants-1996_05
Patent number
US05521188

Linked notes

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