Iron Catalysts [Cross-coupling Reaction using Transition Metal Catalysts]

　Including palladium catalysts, which are frequently used for the Suzuki-Miyaura coupling reaction, transition metal catalysts, such as nickel, copper, or rhodium, have been widely used for organic synthesis. However, the percentages of these metals in the earth’s crust are extremely small, and their prices are rather expensive.¹⁾ On the other hand, iron is abundant and less expensive, therefore, more and more chemists have focused their attention to organic synthesis using iron compounds as a catalyst.
　For instance, with regards to the reactions of Grignard reagents with alkyl bromides, Hayashi et al.²⁾ and Chai et al.³⁾ have reported the synthetic methods using Fe(acac)₃ as a catalyst, Fe(OAc)₂ as a catalyst and Xantphos as a ligand, respectively, by which the desired coupling products can be obtained in good yields.