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

Abstract

AbstractPropargyl 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 POCl3. On the other hand, some substituted pyrazole can be converted to pyrazolo[4,3‐c]cinnoline and pyrazolo[4,3‐c]quinoline.