Knorr pyrazole synthesis

What is Knorr pyrazole synthesis?

The Knorr pyrazole synthesis is a chemical process that involves the formation of pyrazole derivatives through the condensation of hydrazines, hydrazides, semicarbazides, and aminoguanidines with 1,3-dicarbonyl compounds. When substituted hydrazines are used, two structurally isomeric pyrazoles are produced. The reaction is named after Ludwig Knorr, a renowned German chemist who lived from 1859 to 1921.

Knorr pyrazole synthesis
Knorr pyrazole synthesis

References

  • Knorr, L. (1883), Einwirkung von Acetessigester auf Phenylhydrazin. [Effect of acetoacetic ester on phenylhydrazine.] Ber. Dtsch. Chem. Ges., 16: 2597-2599. https://doi.org/10.1002/cber.188301602194
  • Knorr, L. and Blank, A. (1885), Ueber die Einwirkung des Benzoylacetessigesters auf Phenylhydrazin. [On the effect of benzoylacetoacetic ester on phenylhydrazine.] Ber. Dtsch. Chem. Ges., 18: 311-317. https://doi.org/10.1002/cber.18850180155
  • Knorr, L. (1894), Untersuchungen in der Pyrazolreihe. Ueber die Constitution des Pyrazols. [Investigations in the pyrazole series. On the constitution of pyrazole.] Justus Liebigs Ann. Chem., 279: 188-232. https://doi.org/10.1002/jlac.18942790113
  • Knorr, L. (1894), II. Ueber die Condensation von Methylhydrazin mit β-Diketonen. [II. On the condensation of methylhydrazine with β-diketones.] Justus Liebigs Ann. Chem., 279: 232-236. https://doi.org/10.1002/jlac.18942790114
  • Knorr, L. and Oettinger, B. (1894), V. Notiz über die Condensation von Hydrazin mit Dimethylacetylaceton. [Note on the condensation of hydrazine with dimethylacetylacetone.] Justus Liebigs Ann. Chem., 279: 247-248. https://doi.org/10.1002/jlac.18942790117

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