Electric Literature of C6H8N2O2On October 31, 1991 ,《Synthesis of 5-chloropyrazoles by chlorodediazoniation with sulfur dioxide》 appeared in Journal of Heterocyclic Chemistry. The author of the article were Yamamoto, Susumu; Morimoto, Katsushi; Sato, Toshiaki. The article conveys some information:
A facile synthesis of 5-chloropyrazoles I (R = Cl, R1 = Me, R2 = H, R3 = CO2Me, CO2Et, CN; R1 = Ph, R2 = H, R3 = CO2Et; R1 = R2 = Me, R3 = CO2Et) from 5-aminopyrazoles I (R = NH2) via diazotization followed by chlorodediazoniation is described. A new application of sulfur dioxide as a catalyst for the chlorodediazoniation of diazonium chlorides I (R% = N2+Cl-). In the experiment, the researchers used Methyl 1-methyl-1H-pyrazole-4-carboxylate(cas: 5952-93-2Electric Literature of C6H8N2O2)
Methyl 1-methyl-1H-pyrazole-4-carboxylate(cas: 5952-93-2) belongs to pyrazoles. Pyrazoles and their related multiring analogs are common elements of a wide variety of bioactive compounds. These ring structures are rare in nature. A consequence of this is that they have previously been thought to be poor moieties to include in potential new drugs. Electric Literature of C6H8N2O2
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics