1H-Indole, 6-methyl- → 6-methyl-2,3-dihydro-1H-indole

HRID 1598000Notes

Reaction equation

HRID 1598000 reaction equation
[CH3:1][C:2]1[CH:10]=[C:9]2[C:5]([CH:6]=[CH:7][NH:8]2)=[CH:4][CH:3]=1>CCOCC>[CH3:1][C:2]1[CH:10]=[C:9]2[C:5]([CH2:6][CH2:7][NH:8]2)=[CH:4][CH:3]=1

Participants

3

Reactant 1

HCID 1379281H-Indole, 6-methyl-

Product 1

HCID 122033306-methyl-2,3-dihydro-1H-indoleYield 90%

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent2×

Conditions

Temperature
22 °C

Procedure

6-Methylindole (2.785 g, 21.2 mmol) in dry Et2O (30 mL) was chilled to 0° C. and a solution of ZnBH4 in Et2O (~1.5 eq.; 215 mL of 0.15M) was added. The mixture was stirred 3 days at 22° C. in darkness and then quenched by addition of 1M aqueous HCl (until no further H2(g) evolved on mixing) followed by basification to pH >10 with 2N NaOH. The ether phase was separated and washed with brine, tided over MgSO4(s), filtered, and concentrated in vacuo to afford >90% pure 6-methyl-indoline as a syrup (2.82 g; GC/MS: RT=0.63 min., M+ =133). This material can be purified by chromatography on silica (25% EtOAc/hexanes) or vacuum distillation but was typically used without further purification. The following indolines were prepared in an analogous manner from the appropriately substituted indoles:

Workup

  1. customquenched by addition of 1M aqueous HCl (until no further H2(g)
  2. additionon mixing)
  3. customThe ether phase was separated
  4. washwashed with brine
  5. filtrationfiltered
  6. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-5cae78b0ab5747dd8a02007829eb2be8
Source dataset
uspto-grants-1998_04
Patent number
US05736534

Reaction notes

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