Cyclic diaryliodonium ions: old mysteries solved and new applications envisaged

For a long time the unusually poor reactivity of cyclic diaryliodonium ions toward nucleophiles remained a mystery. Only very recently has a solution to this puzzle been found, shedding light on the mechanism of aromatic nucl eophilic substitution reactions of iodonium salts. This article provides an overview of the most important current advances in the field, both theoret ical and practical.