Nucleophilic vinylic substitutions of λ3-vinyliodanes

Because of the excellent nucleofugality of the λ3-phenyliodanyl group, which shows a leaving group ability about 106 times greater than triflate, λ3-vinyl(phenyl)iodanes serve as highly reactive species in nucleophilic substitutions. This review summarizes the nucleophilic vinylic substitutions of λ3-vinyl(phenyl)iodanes. The reaction rates and mechanism of the nucleophilic vinylic substitutions change depending on the structure of λ3-vinyliodanes; the nature of the substituents at the β-vinylic carbons is especially important. β-Monoalkyl-λ3-vinyliodanes undergo bimolecular nucleophilic vinylic substitutions (SN2) with exclusive inversion of configuration under mild conditions, which, hitherto, has been considered to be impossible on the bases of experimental results and theoretical calculations. Vinylic SN1 reactions generating vinyl cations, ligand coupling reactions on hypervalent iodine(III), and addition–elimination and elimination–addition reactions, are also discussed.