α-vinylation of 1,3-dicarbonyl compounds with alkenyl(aryl)iodonium tetrafuoroborates: effects of substituents on the aromatic ring and of radical inhibitors

摘要

Direct α-vinylations of enolate anions derived from 1,3-dicarbonyl compounds with 4-tert-butyl-1- cyclohexenyl(aryl)iodonium 2 and 1-cyclopentenyl(aryl)iodonium tetrafluoroorates 3 are reported. Frequently, α-phenylations compete with the vinylations in the reaction of 1,3-dicarbonyl compounds With alkenyl(phenyl)iodonium salts 2a and 3a, Use of alkenyl(p-methoxyphenyl)iodonium salts 2b and 3b, however, leads to selective α-vinylation at the expense of the competing arylation of 1,3-dicarbonyl compounds.