Synthesis of Substituted Pyrazole N ‐Oxide and Pyrazole from Propargyl Amine

This is the authors' abstract. We don't add key points for this paper.

Propargyl amine can be efficiently converted to pyrazole N ‐oxide from the reaction of sodium nitrite in acetic acid catalysed by AgOTf in excellent yields. The pyrazole N ‐oxides can be converted into pyrazole by treatment of phosphorous trichloride in refluxing chloroform. The pyrazole N ‐oxide could be converted to highly substituted 4‐chloropyrazole by treating DMF and POCl 3 . On the other hand, some substituted pyrazole can be converted to pyrazolo[4,3‐ c ]cinnoline and pyrazolo[4,3‐ c ]quinoline.