Internal delivery of soft chlorine and bromine atoms: Stereoselective synthesis of (E)-β-halogenovinyl(aryl)-λ³-iodanes through domino λ³-lodanation-1,4-halogen shift-fluorination of alkynes

X = Cl, Br; n = 1-3 4-(Difluoroiodo)toluene-induced domino λ³-iodanation-1,4-halogen shift-ring enlargement-fluorination reaction of 5-halopentynes with a four-, five-, or six-membered carbocycle afforded the ring-expanded (E)-δ-fluoro-β-halovinyl- λ³-iodanes stereoselectively in high yields, probably via the intermediacy of five-membered halonium ions. Use of internal alkynes makes it possible to synthesize tetrasubstltuted β-halovinyl-λ³- iodanes with defined stereochemistry.