Abstract The indoles 3, 5, 7, 9 and 11 yield xanthenylindoles in the reaction with the SN 1- active reagent xanthydrole (1) by acid catalysis. The regioselectivity of this electrophilic heteroaromatic substitution is predominantly controlled by the acid concentration, by the temperature and by the stoichiometric composition of the reactants. An order of positions which is supported by selectivity on the indole nucleus is presented in the experimental ...
