10505-21-2

Upstream product

• 75239-15-5 4-acetyl-1-methylpyrazole-3-carboxylic acid 
• 33090-56-1 3-cyano-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester 
• 25016-12-0 1,3-dimethyl-1H-pyrazole-4-carbaldehyde 
• 75239-14-4 ethyl 4-acetyl-1-methylpyrazole-3-carboxylate 
• 191418-75-4 3-Hydroxythiocarbamoyl-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester 
• 191418-67-4 5-[(E)-Hydroxyimino]-4-oxo-4,5-dihydro-thiophene-3-carboxylic acid ethyl ester 
• 1006-44-6 4-hydroxy-3-methyl-3-thiophenecarboxylic acid ethyl ester 
• 57397-70-3 ethyl 3-(ethoxymethylene)-2,4-dioxovalerate 

Relevant academic research and scientific papers

Electrosynthesis of pyrazole-4-carboxylic acids by oxidation of 4-formylpyrazoles on NiO(OH)-electrode in aqueous alkaline solution

Electrochemical oxidation of di- and trisubstituted 4-formylpyrazoles on a Ni-anode in aqueous alkali led to the formation of the corresponding pyrazole-4-carboxylic acid in 60-90% yields. The yields of the target products depend on position of substituent in the pyrazole ring and are decreased in the following sequence of substituent at position 1 Me > Et > Ph, as well as when the aqueous medium was replaced with aqueous alcohol (50% Bu tOH). Oxidation of 4-formylpyrazoles containing Me groups at the carbon atoms of the pyrazole ring led, to monoacids and also pyrazoledicarboxylic acids in small (1.5-14%) amounts; the latter were the oxidation products of the aldehyde and the Me groups.

Reaction of 4-Hydroxy-5-oximino-3-thiophenecarboxylates with Hydrazines. Formation of Pyrazolylthiohydroxamic Acids

The reactions of 4-hydroxy-5-oximino-3-thiophenecarboxylates with hydrazine and substituted hydrazines have been investigated. The products of the reactions have been shown to be pyrazole-3- or 5-thiohydroxamic acids rather than the hydrazones previously described by Benary and Silberstrom. Two alternate mechanisms are proposed which account for the regiochemical outcome. The structures of the pyrazole-3- and 5-thiohydroxamic acids and corresponding nitriles have been proven by independent synthesis, comparison to known compounds, and by proton and carbon magnetic resonance and long range HETCOR experiments.

Reaction of Ethyl 3-Ethoxymethylene-2,4-dioxovalerate with Monosubstituted Hydrazines

Reactions of ethyl 3-ethoxymethylene-2,4-dioxovalerate (1) with phenyl- and methylhydrazines are described.While the reaction of 1 with phenylhydrazine gave a mixture of ethyl 4-acetyl-1-phenylpyrazole-5-carboxylate (4) and ethyl 5-methyl-1-phenylpyrazole