[chemical substances]
   reactive intermediates
     Class dipolar compounds
       Class 1,3-dipolar compounds
         Class Propargyl type 1,3-dipolar compounds [X≡N+-Z <-> X-=+N=Z <-> X-=NZ+ <-> XN=Z (X=C,O; Z=C,N,O)]
           Class azides [RN=N+=-N]