Transition‐Metal‐free C5, C7‐Dihalogenation and the Switchable C5 Halogenation of 8‐Hydroxyquinolines

Abstract The first example on the C5, C7‐dihalogenation of 8‐hydroxyquinolines based on an in situ O ‐acyl 8‐hydroxyquinoline formation is realized under catalyst‐free condition in toluene. Modifying the reaction conditions by directly utilizing O ‐acylated 8‐hydroxyquinolines in the presence of AlCl 3 enables the electrophilic halogenation in the C5 position, leading to the tunable synthesis of C5 halogenated products. The O ‐acyl group can be easily removed from the product to provide halogenated quinolines containing free hydroxyl group by simple hydrolysis.