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

摘要

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 POCl3. On the other hand, some substituted pyrazole can be converted to pyrazolo4,3-c cinnoline and pyrazolo4,3-c quinoline.