Relay catalysis by a multifunctional Cu catalyst in a tandem dehydro-/dehalogenation sequence along with N-arylation.

A Cu-catalyzed tandem dehydrogenation/dehalogenation sequential reaction along with N-arylation has been developed for the synthesis of pyridazinone derivatives in an aerobic and aqueous environment. To achieve the transformation of three chemical bonds in a one-pot reaction, a multifunctional copper catalyst was used which afforded excellent activity, high selectivity, and recyclability. The catalytic system consists of a water-soluble Cusalen complex and Na2CO3 in neat water and an air atmosphere.