- Palladium-catalyzed annulation of vinylic cyclopropanes and cyclobutanes
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Aryl iodides substituted in the ortho position by OH, CH2OH, NH2, NHTs and CH(CO2Et)2 groups react with vinylic cyclopropanes and cyclobutanes in the presence of a palladium catalyst and an appropriate base to afford good yields of heterocycles and carbocycles. The annulation products apparently arise by (1) palladium(0) formation and insertion into the carbon-iodine bond of the aryl iodide to generate an arylpalladium intermediate, (2) arylpalladium addition across the carbon-carbon double bond of the alkene, (3) ring-opening of the cyclopropane or cyclobutane by carbon-palladium beta elimination, (4) rearrangement of the resulting unsaturated alkylpalladium compound to a π-allylpalladium compound by a series of reversible palladium hydride beta elimination and readdition steps, (5) anion formation by removal of a proton from the functional group present on the arene, and (6) nucleophilic substitutions of the palladium by the resulting anion.
- Larock, Richard C.,Eul Kgun, Yum
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p. 2743 - 2758
(2007/10/03)
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