Regioselectivity in aromatic electrophilic substitution continues to attract chemical research even though the reaction is over 100 years old. The problem is this regioselectivity can be difficult to achieve. Take a monosubstituted arene, throw a chemical at it and see where it ends up. In a totally unspecific reaction the new substituent can occupy one of 3 different positions (ortho, meta or para) and with multiple substitutions the mix gets even more complicated. Regioselectivity can be introduced by so-called directing groups. Activating groups promote ortho and meta substitution and deactivating groups that of meta substitution. But what to do with them when the reaction is done?. An old trick that gets rediscovered from time to time is the use of a removable directing group. A classic is the sulfonic acid group in aromatic sulfonation or the carboxyl group. Recent case studies involving removable directing group are those on pyridyl silyl groups DOI, carboxyl groups DOI and cyano groups DOI.