An Efficient Copper-mediated 1,3-Dipolar Cycloaddition of Pyrazolidinone-based Dipoles to Terminal Alkynes to Produce N,N-Bicyclic Pyrazolidinone Derivatives

A simple dinuclear copper complex [Cu(mu-OH)(tmen)](2)Cl-2 (tmen = N,N,N',N'-tetramethylethylenediamine) could act as an effective precatalyst for the 1,3-dipolar cycloaddition of pyrazolidinone-based dipoles to terminal alkynes to produce the corresponding N,N-bicyclic pyrazolidinone derivatives