AgNO2 as the NO Source for the Synthesis of Substituted Pyrazole N‑Oxides from N‑Propargylamines

A straightforward method for synthesizing the pyrazole N-oxides from N-propargylamines and AgNO2 through oxidation/cyclization reaction had been developed. AgNO2 was used as the NO source for the first time to synthesize pyrazole N-oxides. Various substituted groups on N-propargylamines proceeded smoothly, and the desired products were obtained in good yields.