Reactions of 1,4-Dianion of Methyl 2-Thienyl Ketone N-Ethoxycarbonylhydrazone with Derivatives of Carboxylic Acids,and the Synthesis of Pyrazolotriazin-7-ones

1,3,5-trisubstituted pyrazoles were obtained by reaction of carboxylic acids derivatives with 1,4-dianion of methyl 2-thienyl ketone N-ethoxycarbonylhydrazone. The dianion was prepared by treating the hydrazone with butyllithium in THF at -78°C. Besides were prepared 4-methyl (or 4-phenyl)-2-(2-thienyl)-6H-pyrazolo1,5-d]1,2,4]triazin-7-ones from the corresponding 1,3,5-trisubstituted pyrazoles synthesized respectively with the use of ethyl pyruvate and ethyl phenylglyoxylate.