The article reports on the formation of Cyclopentadienone derivatives by the reaction of 1,4,-Dilithio-1,3-dienes or Zirconacyclopentadienes with Oxalyl Chloride in the presence of CuCI. The article reports the first 1,1-cycloaddition of oxalyl chloride with 1,4-dilithio-1,3-dienes or zirconcyclopentadienes to afford cyclopentadienone derivatives in the presence of CuCl, in which the carbon-carbon bond of 1 ,2-dicarbonyl cleaved during nucleophilic addition. To avoid the high reactivity of organodilithium compound, a proper tuning of the reactivity of organodimetallic reagents and oxalyl chloride is possible.