Nickel-Catalyzed Bromide-to-Iodide Aromatic Finkelstein Reaction

Key words

nickel catalysis - aryl iodides - halogen exchange

Significance

In 1978, Takagi, Hayama, and Okamoto disclosed an early example of a halogene exchange reaction using a simple nickel(II) precatalyst, with added Zn or PBu₃, and a nucleophilic source of iodide (KI). As the authors explain, at this time the most common strategy to perform an aromatic Finkelstein reaction was to use copper; however, the ability to go from a bromide to iodide was unattainable. This topic has remained of interest for the last 50 years, with notable contributions from a wide variety of groups.

 

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Review

D. A. Petrone, J. Ye, M. Lautens Chem. Rev. 2016, 116, 8003–8104.

 

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Comment

The addition of Zn was crucial for the reaction to occur at lower temperatures. Moreover, it was found that the addition of a donating phosphine ligand, such as PBu₃, suppressed the formation of the reductive homocoupled side product. At elevated temperatures, only the phosphine additive was necessary for a successful reaction, without the need of the Zn reductant. The reaction did not occur when using various nickel(0) precatalysts.

 

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Publication History

Article published online:
16 February 2022