1-Methyl-2,3-dihydro-1H-indole → 1-Methylindole

HRID 970073Notes

Reaction equation

HRID 970073 reaction equation
[CH3:1][N:2]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH2:4][CH2:3]1>C1(C)C=CC=CC=1.O=[Mn]=O>[CH3:1][N:2]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH:4]=[CH:3]1

Participants

4

Reactant 1

HCID 558301-Methyl-2,3-dihydro-1H-indole

Product 1

HCID 117811-MethylindoleYield 57%

Reagents, catalysts & solvents 2

HCID 14801Manganese dioxideCatalystHCID 1140TolueneSolvent

Procedure

The N-methyl indoline product in Example 47 (70 mg, 0.22 mmol) was dissolved in toluene (9 mL) in a 50-mL flask under N2 fitted with a condenser. MnO2 (199 mg, 2.3 mmol) was added, and the mixture was heated to reflux for 1.5 h. The mixture was cooled to rit, Celite, and the pad was washed several times with liberal amounts of MeOH. The filtrate was concentrated in vacuo, and the residue was purified by silica gel chromatography (gradient 25-35% EtOAc/hexane) to provide the N-methyl indole product (39 mg, 57%) as an orange oil: 1H NMR (300 MHz, CDCl3) δ 6.93-7.11 (m, 5H), 6.72 (d, J=8.5 Hz, 1H), 6.42 (d, J=3.1 Hz, 1H), 4.29 (t, J=5.8 Hz, 1H), 3.84-3.96 (m, 2H), 3.77 (s, 3H), 2.99 (dd, J=11.3, 5.0 Hz, 1H), 2.67 (dd, J=11.3, 6.7 Hz, 1H), 2.49 (s, 3H); ESI MS m/z=313[C19H18F2N2+H]+.

Workup

  1. customfitted with a condenser
  2. temperaturethe mixture was heated
  3. temperatureto reflux for 1.5 h
  4. temperatureThe mixture was cooled to rit, Celite
  5. washthe pad was washed several times with liberal amounts of MeOH
  6. concentrationThe filtrate was concentrated in vacuo
  7. customthe residue was purified by silica gel chromatography (gradient 25-35% EtOAc/hexane)

Sources & evidence

ORD record
ord-bb87ee6e1d9848a88dc869116b68b742
Source dataset
uspto-grants-2007_12
Patent number
US07309789B2

Reaction notes

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