What is Negishi Coupling?

        Negishi coupling is a relatively new process that is used to make new carbon-carbon single bonds. In this process, an organometallic (i.e. Grignard) reagent is formed (Fig. 1) which can attack at any electrophilic center. The difference between Negishi coupling and a traditional Grignard organometallic reaction is that Negishi coupling allows the nucleophilic organometallic reagent to attack more complex systems, including aromatic rings and double bonds. Higher yields are recorded when a palladium catalyst are used. It is believed that the palladium catalyst is able to insert itself in the carbon-halogen bonds that are breaking, thus ‘weakening’ them and allowing the reaction to proceed (Fig. 2).