Potassium Carbonate → Indole

HRID 1602098Notes

Reaction equation

HRID 1602098 reaction equation
N1N=C[N:4]([C:6]2[CH:11]=[CH:10][C:9](NN)=[CH:8][CH:7]=2)[CH:5]=1.[CH3:14]OC(OC)CCCCN1CCN(C(OC(C)(C)C)=O)CC1.C([O-])([O-])=O.[K+].[K+]>S(=O)(=O)(O)O>[NH:4]1[C:6]2[C:7](=[CH:8][CH:9]=[CH:10][CH:11]=2)[CH:14]=[CH:5]1

Participants

5

Reactant 3

HCID 11430Potassium CarbonateHCID 51624184-(4-hydrazinylphenyl)-4H-1,2,4-triazoleHCID 10829224HCID 10829224, compound

Product 1

HCID 798IndoleYield 116.4%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent

Procedure

A mixture of 4-(1,2,4-triazol-4-yl)phenylhydrazine (5.0 g, 28.6 mmol) and 5-[4-(tert-butyloxycarbonyl)piperazin-1-yl]pentanal dimethyl acetal (9.03 g, 28.6 mmol) in 4% sulphuric acid (150 ml) was heated at reflux for 48 h. The solution was cooled in an ice-bath, basified with solid K2CO3 and extracted with butan-1-ol (×3). The solvent was removed under vacuum and azeotroped with hexane (×2). The crude product was purified by chromatography on silica gel eluting with CH2Cl2 /MeOH/NH3 (30:8:1) to give the title-indole (3.9 g, 44%). δ(360 MHz, oxalate salt in D2O) 2.12-2.24 (2H, m, CH2); 2.93 (2H, t, J=7 Hz, CH2); 3.46-3.76 (8H, m, 4 of CH2) 7.37 (1H, dd, J=1.9 and 8.7 Hz, Ar-H); 7.39 (1H, s, Ar-H); 7.66 (1H, d, J=8.7, Ar-H); 7.82 (1H, d, J=1.9 Hz, Ar-H); 9.13 (2H, s, Triazole-H).

Workup

  1. temperaturewas heated
  2. temperatureat reflux for 48 h
  3. temperatureThe solution was cooled in an ice-bath
  4. extractionextracted with butan-1-ol (×3)
  5. customThe solvent was removed under vacuum
  6. customazeotroped with hexane (×2)
  7. customThe crude product was purified by chromatography on silica gel eluting with CH2Cl2 /MeOH/NH3 (30:8:1)

Sources & evidence

ORD record
ord-111e539db6354bd08e4b2dc10513d351
Source dataset
uspto-grants-1999_11
Patent number
US05981529

Reaction notes

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