Alkenyliodonium tetrafluoroborates

Alkenyliodonium tetrafluoroborates (14,10-11). On treatment with base these salts can undergo elimination of iodobenzene to generate a carbenoid that undergoes 1,5-C—H insertion (equation I). This elimination can compete with a 1,2-... 

Preparation First representatives of alkenyliodonium salts, dichlorovinyl(phenyl)iodonium species, were reported by Thiele and Haakh in the early 1900s [436]. The first general synthetic approach to alkenyl(phenyl)iodonium salts was developed by Ochiai in the mid-1980s [437,438], This method is based on the reaction of silylated alkenes 299 with iodosylbenzene in the presence of Lewis acids, leading to the stereoselective formation of various alkenyliodonium tetrafluoroborates 300 in good yield (Scheme 2.85). 

It has been shown that selective a-vinylation of enolate anions derived from 1,3-dicarbonyl compounds can be achieved by reaction with 4-/-butyl-1 -cyclohcxcnyl-(aryl)iodonium and 1 -cyclopentenyl(aryl)iodonium tetrafluoroborates without competing a-arylation, provided that the alkenyliodonium salt used bears a / -mcthoxyphcnyl, rather than phenyl, group.24... 

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