Ringtransformation of Ethyl 2-Amino-thiophene-3-carboxylates: Derivatives of Pyridones and Pyridazinones

Article abstract of DOI:10.1007/BF00810107

Whereas treatment of the ethyl 5-acetyl-2-amino-4-methyl-thiophene-3-carboxylate (1) with potassium hydroxide yields the 2-hydroxy-thiophene-3-carbonitrile 4 its hydrazone 2 is converted into the 1-amino-5-mercapto-2-pyridone derivative 6.The transformation of the 2-amino-5-phenylazo-thiophene derivative 9 by potassium hydroxide yields the substituted 3-mercapto-pyridazin-6(1H)one 10, with sodium ethoxide the 5-phenylhydrazone-2-oxo-thiolen-3-carbonitrile 11 is formed.From 6 the 5-mercapto-2-pyridone derivatives 7d, e can be obtained. - Keywords: 2-Aminothiophene-3-carboxylic acid derivatives; 1-Amino-2-pyridone; 1,2-Dihydro-2-oxo-pyridine-5-thioles; Pyridazin-6(1H)-one