The Halogen‐Samarium Exchange Reaction. Synthetic Applications and Kinetics

Fast I/Sm‐ and Br/Sm‐exchanges take place when treating various aromatic or heterocyclic iodides and bromides with nBu2SmCl·4LiCl or nBu3Sm·5LiCl respectively. The resulting organosamarium reagents were efficiently quenched with aldehydes, ketones, and imines. Also, they undergo acylations when treated with N,N‐dimethylamides leading to ketones. The rate of the Br/Sm‐exchange on a typical aryl bromide was determined and showed that it was 8.5·105 faster than the Br/Mg‐exchange, supporting that the rate of a metal‐exchange is related to the ionic character of the carbon‐metal bond and to the metal electronegativity.

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