Novel regioselective aromatic chlorination via catalytic thiourea activation of N-chlorosuccinimide

A metal and acid-free electrophilic aromatic chlorination methodology involving catalytic thiourea activation of N-chlorosuccinimide (NCS) is reported herein. Moderate yields and regioselectivities of chlorinated aromatics were obtained using a combination of 1.05-1.15 equiv of NCS and 5 mol % of thiourea at room temperature in acetonitrile. A halogen bond between the sulfur atom of thiourea and the sigma-hole of the NCS chlorine atom is thought to enhance the electrophilic activity of the chlorine of NCS. (C) 2015 Elsevier Ltd. All rights reserved.