Pechmann 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:



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