Alpha-Methylstyrene → Ethyl 2-amino-1-benzothiophene-3-carboxylate

HRID 2086330Notes

Reaction equation

HRID 2086330 reaction equation
C([NH:4][CH:5]1[CH:9]([C:10]([O:12][CH2:13][CH3:14])=[O:11])[CH:8]2[CH2:15][CH:16]=[CH:17][CH:18]=[C:7]2[S:6]1)(=O)C.CC(C1C=CC=CC=1)=C.N1CCCC1>C1(C)C(C)=CC=CC=1>[NH2:4][C:5]1[S:6][C:7]2[CH:18]=[CH:17][CH:16]=[CH:15][C:8]=2[C:9]=1[C:10]([O:12][CH2:13][CH3:14])=[O:11]

Participants

5

Reactant 3

HCID 7407Alpha-MethylstyreneHCID 31268PyrrolidineHCID 69889442HCID 69889442, compound

Product 1

HCID 699464Ethyl 2-amino-1-benzothiophene-3-carboxylateYield 70.5%

Reagents, catalysts & solvents 1

HCID 7237O-XyleneSolvent

Conditions

Temperature
102 °C

Procedure

14.4 g of hydrogenation catalyst (Degussa-Hüls; E 101 R/W 5%) are added to a solution of 36 g of ethyl 2-acetylaminotetrahydrobenzothiophene-3-carboxylate in 250 ml of xylene (isomeric mixture) and the mixture is heated to a constant temperature of 139° C. to 141° C. 47 g of α-methylstyrene are metered in over a period of 5 h. The mixture is then refluxed for a further 36 h. It is cooled to 102° C., 32 g of pyrrolidine are added and the mixture is brought back to the reflux point (127° C.); it is stirred for 20 h at this temperature. After cooling to 20° C., the Pd/carbon is filtered off, the filtrate is concentrated to a residue, and the residue is taken up in 75 ml of ethyl acetate and washed with three times 12 ml of 10% hydrochloric acid. The organic phase is washed with twice 5 ml of water and then concentrated to a residue. This is recrystallized from 50 ml of isopropanol to give 21 g of ethyl 2-aminobenzothiophene-3-carboxylate in the form of slightly yellowish crystals (70.5% yield).

Workup

  1. temperaturethe mixture is heated to a constant temperature of 139° C. to 141° C
  2. customare metered in over a period of 5 h
  3. temperatureThe mixture is then refluxed for a further 36 h
  4. customis brought back to the reflux point (127° C.)
  5. temperatureAfter cooling to 20° C.
  6. filtrationthe Pd/carbon is filtered off
  7. concentrationthe filtrate is concentrated to a residue
  8. washwashed with three times 12 ml of 10% hydrochloric acid
  9. washThe organic phase is washed with twice 5 ml of water
  10. concentrationconcentrated to a residue
  11. customThis is recrystallized from 50 ml of isopropanol

Sources & evidence

ORD record
ord-19b77b8a566d43ca85744ad25a9275bb
Source dataset
uspto-grants-2004_04
Patent number
US06723848B2

Reaction notes

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