297. Pechmann Pyrazole Synthesis

H. v. Pechmann, Ber. 31, 2950 (1898).

Formation of pyrazoles from acetylenes and diazomethane. The analogous addition of diazoacetic esters to the triple bond yields pyrazolecarboxylic acid derivatives:

Chemical reaction

References

R. A. Raphael, Acetylenic Compounds in Organic Synthesis (London, 1955) p 179; T. L. Jacobs, Heterocycl. Compd. 5, 70 (1957); B. Eistert et al., Houben-Weyl 10/4, 840 (1968). Cf. Knorr Pyrazole Synthesis.