AbstractIntramolecular nucleophilic displacement in organic fluorine compounds takes place if a fluorine atom is located in the molecule at such a distance from a nucleophilic functional group as to allow cyclization to three‐membered rings (in aliphatic compounds only), five‐membered rings, six‐membered rings, and, exceptionally, seven‐ and polymembered rings (in aromatic series only). The nucleophilic functions can be hydroxyl groups of alcohols, enols, phenols and carboxylic acids, sulfhydryl groups, primary or secondary amino groups, and carbanionic carbon atoms. The reaction is common with aliphatic monofluorides and aromatic polyfluorides, and rare with geminal and trigeminal fluorides. Whereas in the aliphatic series it is usually an undesirable side‐reaction, in the aromatic series it is useful as a means of synthesizing carbocyclic and heterocyclic polynuclear