Interaction of an Allene with Polyvalent Iodine Derivatives. Preparation, X-ray Molecular Structure, and Some Reactions of Phenyl(2,2-dimethyl-4-(diethylphosphono)-2,5-dihydro-3-furyl)iodonium Salts

Aliene 1 reacts with PhIO/BF₃·Et₂O or PhIF₂/BF₃·Et₂O in CH₂Cl₂ at −60 °C with the formation of novel phenyldihydrofuryliodonium salts 2. Molecular structures for both products 2a,b are determined by X-ray analysis. Iodonium perchlorate 2b reacts with the anionic nucleophiles (NaN₃, NaOCH₃, NaOC₂H₅, CuI/KI) to give the corresponding products of the vinylic nucleophilic substitution (6a‒e) of the iodobenzene moiety. However, analogous reaction of 2b with Ph₃P gives an unexpected iodide 6e as the major product, along with the usual product of nucleophilic substitution (6d). This result is rationalized by a nucleophilic attack of Ph₃P on the iodine atom of the iodonium salt 2b followed by two alternative paths for subsequent ligand coupling.