Reaction of Magnesium Reagent Having C-Mg, N-Mg and O-Mg Bonds
--Entire Features of Reactions and Exact Use of Reagents--

Masao OKUBO* and Koji MATSUO

Department of Chemistry, Saga University, Honjo-machi, Saga-shi 840-0027 Japan

In the reactions of reagents having C-Mg, N-Mg and O-Mg bonds with substrates having functional groups (NO2, CO, CN), distribution of the normal (addition and condensation) and abnormal (radical) products is correlated with the values of difference between oxidation and reduction potentials of the reactants (ΔE=EoxEred) which estimate the relative efficiency of single electron transfer (SET). The study is called ΔE-approach.
Mild reactivity of the N-Mg reagent derived from anilines is profitable for disclosure of factors governing all of the reactions of the reagent to allow all of those to be classified and characterized. It was found that the use of strongly coordinating ligands as additives led to disclosure of the implicit SET in large ΔE reaction, which was also useful for improvement of the yield of the normal products.
Two essential features (I and II) of the reactions are derived: I) Participation of SET and σ-complexation (e.g. >C=OEEEMg<) is necessary for the formation of normal products from the reaction components; and II) an excess amount of reagent assists later step of the reaction (i.e., radical transfer leading to product formation). Feature II) implies that the later step proceeds in an assembly composed of the generated pair of radical species and excess reagent molecules (i.e., in a closed environment), this feature being considered to validate the ΔE-approach stating that the most basic one of initial conditions (i.e., potential difference) relates to the final distribution of products even in the multistep reactions. Basic guide lines for exact use of the magnesium reagents are thus given.

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