Gewald condensation of ketone with cyanoester/S8; Ethyl 2-amino-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate
SyntheticPage 407
DOI:
10.1039/SP407
Submitted May 06, 2010, published May 06, 2010
Chemicals Used
Ethyl cyanoacetate (TCI)
Sulfur (Wako)
Diethylamine (TCI)
Cyclohexanone (TCI)
Procedure
To a solution of ethyl cyanoacetate (5.0 mL, 47 mmol), sulfur (1.5 g, 47 mmol), diethylamine (4.2 mL, 82 mmol) in DMF (15 mL) was added cyclohexanone (4.8mL, 47 mmol) dropwise at room temperature. After stiiring at 60 °C for 3 h, the mixture was cooled to room temperature. Water (100 mL) was added to the mixture and precipitated yellow solid was filtered and washed with water (100 mL) and dried in vacuo to give the product (9.0g, 40 mmol, 85%).
Author's Comments
We have synthesized many kinds of thiophene derivatives with this method. In some cases column chromatography is required because of no precipitation is observed.
Data
1H NMR 400 MHz (CDCl3) d ppm 7.20 (br, 2H), 4.14 (q, 2H, J = 7.1 Hz), 2.59 (m, 2H), 2.50 (m, 2H), 2.41(m, 2H), 1.66 (m, 4H), 1.24 (t, 3H, J = 7.1 Hz).
Lead Reference
M. Perrissin, C. L. Duc, G. Narcisse, F. Bakri-Logeais, F. Huguet, Eur. J. Med. Chem. 1980, 15, 413-418
Supplementary Information
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Keywords: amines, aromatics/arenes, carbocyclic compounds, cyclization, esters, heterocyclic compounds
