Peculiarities of nucleophilic substitution in indolyliodonium salts

3-Indolylphenyliodonium trifluoroacetate reacts with ammonium bromide and lithium chloride and bromide to give 3-haloindoles. The reaction with ammonium chloride and tetrabutylammonium chloride leads to a mixture of 2- and 3-chloroindoles. The same mixture of chloroindoles is also formed by the action of lithium chloride but in the presence of 15-crown-5 ether. The course of the reaction is explained by ambident reaction of the cation of the iodonium salt.