2-Amino-4,5-dimethyl-3-thiophenecarboxylic Acid Ethyl Ester is used in the preparation triazine and pyrimidine derivatives as anti-inflammatory and analgesic agents. Also used in the synthesis of antioxidants through heteroaryl amines as well as CB2 cannabinoid receptor partial agonists.
To a 100-mL round-bottomed flask were added 2-butanone (20 g, 0.28 mol, 1.0 eq.), ethyl cyanoacetate (31.4 g, 0.28 mol, 1.0 eq.), and sulfur powder (8.9 g, 0.28 mol, 1.0 eq.), followed by ethanol as a solvent. Diethylamine (21 g, 0.28 mol, 1.0 eq.) was added dropwise to the above mixture. The reaction system was stirred continuously for 8 hours at room temperature. After completion of the reaction, the reaction mixture was diluted with water and the resulting precipitate was collected by filtration. Purification by ethanol recrystallization afforded ethyl 2-amino-4,5-dimethylthiophene-3-carboxylate as a yellow solid (41 g, 75% yield).
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