Radical chemistry, “cation pool

Radical Chemistry Using the Cation Pool Method... 

Carbocations, carbon radicals, and carbanions are important reactive carbon intermediates in organic chemistry and their interconversions could be effected, in principle, by redox processes. With the cation pool method at hand, we next examined the redox-mediated interconversions of such reactive carbon species. 

Radical addition to an Af-acyliminium ion is also an interesting feature of the cation pool chemistry. We found that an alkyl iodide reacted with an N-acyliminium ion pool in the presence of hexabutyldistannane to give coupling product 19.24 A chain mechanism shown in Scheme 10, which involves the addition of the alkyl radical to the N-acyliminium ion to form the corresponding radical cation, seems to be reasonable. The present reaction opens a new possibility for radical-cation crossover mediated carbon-carbon bond formation. 

One novel feature of the chemistry stems from a realization that the initially formed cation pool intermediate can be reduced [13]. An acyliminium ion, for example, can be reduced to the corresponding radical, thereby offering a direct pathway for the formation of these intermediates. The resulting species undergo the usual sorts of reaction that characterize radicals including, for example, being intercepted by electron-deficient alkenes (Eq. 10). 

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