The Scope and Limitations of Intramolecular Radical Cyclizations of Acylsilanes with Alkyl, Aryl, and Vinyl Radicals

5- Exo cyclizations of primary and secondary radicals with acylsilanes successfully give cyclopentyl silyl ethers. The corresponding 6- exo cyclizations are sensitive to changes of the size of silyl groups. Secondary radicals undergo 6- exo cyclizations with acylsilanes more slowly. Reaction of aryl radical with acylsilane proceeds well for 5- exo cyclization but not for 6- exo cyclization. Vinyl radicals give best results in 5- exo cyclizations with acylsilanes but give low yields (∼30%) in 6- exo cyclizations. Intramolecular cyclizations of vinyl radicals with acylsilanes give enol silyl ethers regiospecifically.