Stannous Chloride → Ethyl 6-amino-1H-indole-4-carboxylate

HRID 469977Notes

Reaction equation

HRID 469977 reaction equation
[CH2:1]([O:3][C:4](=[O:22])[C:5]1[CH:10]=[C:9]([N+:11]([O-])=O)[CH:8]=[C:7]([N+]([O-])=O)[C:6]=1[CH:17]=[CH:18][N:19](C)C)[CH3:2].Cl[Sn]Cl>C(O)C>[CH2:1]([O:3][C:4]([C:5]1[C:6]2[CH:17]=[CH:18][NH:19][C:7]=2[CH:8]=[C:9]([NH2:11])[CH:10]=1)=[O:22])[CH3:2]

Participants

4

Reactant 2

HCID 24479Stannous ChlorideHCID 76548813HCID 76548813, compound

Product 1

HCID 53435938Ethyl 6-amino-1H-indole-4-carboxylateYield 40%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

A mixture of 2-(2-dimethylamino-vinyl)-3,5-dinitro-benzoic acid ethyl ester (11.3 g, 0.037 mol) and SnCl2 (83 g, 0.37 mol) in ethanol was heated at reflux for 4 h. The mixture was concentrated to dryness and the residue was poured into water and basified with sat. Na2CO3 solution to pH 8. The precipitate was filtered off and the filtrate was extracted with ethyl acetate (3×100 mL). The combined extracts were washed with water (2×100 mL) and brine (150 mL), dried over Na2SO4 and concentrated to dryness. The residue was purified by column chromatography on silica gel to give 6-amino-1H-indole-4-carboxylic acid ethyl ester (B-18) (3 g, 40%). 1H NMR (DMSO-d6) δ 10.76 (br s, 1 H), 7.11-7.14 (m, 2 H), 6.81-6.82 (m, 1 H), 6.67-6.68 (m, 1 H), 4.94 (br s, 2 H), 4.32-4.25 (q, J=7.2 Hz, 2 H), 1.35-1.31 (t, J=7.2, 3 H). ESI-MS 205.0 m/z (MH+).

Workup

  1. temperaturewas heated
  2. temperatureat reflux for 4 h
  3. concentrationThe mixture was concentrated to dryness
  4. additionthe residue was poured into water and basified with sat. Na2CO3 solution to pH 8
  5. filtrationThe precipitate was filtered off
  6. extractionthe filtrate was extracted with ethyl acetate (3×100 mL)
  7. washThe combined extracts were washed with water (2×100 mL) and brine (150 mL)
  8. dry with materialdried over Na2SO4
  9. concentrationconcentrated to dryness
  10. customThe residue was purified by column chromatography on silica gel

Sources & evidence

ORD record
ord-14b944d52ff84ce4a3d680c05a051e78
Source dataset
uspto-grants-2014_01
Patent number
US08629162B2

Reaction notes

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