How are Catalytic Reactions Possible

The most useful reaction of Pd is a catalytic reaction, which can be carried out with only a small amount of expensive Pd compounds. The catalytic cycle for the Pd(0) catalyst, which is understood by the combination of the aforementioned reactions, is possible by reductive elimination to generate Pd(0), The Pd(0) thus generated undergoes oxidative addition and starts another catalytic cycle. A Pd(0) catalytic species is also regenerated by /3-elimination to form Pd—H which is followed by the insertion of the alkene to start the new catalytic cycle. These relationships can be expressed as shown. 

As a typical example, the catalytic reaction of iodobenzene with methyl acrylate to afford methyl cinnamate (18) is explained by the sequences illustrated for the oxidative addition, insertion, and /3-elimination reactions. 

Hayashi, Chem. Lett.. 2177 (1992) T. Hayashi, A. Kubo, and F. Ozawa, Pure Appl. Chem., 64, 421 (1992). 

Savoia, C. Trombini, A. Utnani-Ronchi, and G. Verardo, Chem. Commun., 540, 541 (1981). 

Maitlis, The Organic Chemistry of Palladium, Vols 1 and 2, Academic Pre.ss, New York, 1971. 

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