Regioselective Palladaelectro-catalyzed Chlorination of Arenes in an Undivided Cell Setup

Chloroarenes constitute fundamental building blocks in organic synthesis and are widely applied in the synthesis of bioactive compounds, fine chemicals, materials, natural products and pharmaceuticals. Electrochemical chlorination has been recognized as a promising synthetic method for accessing chloroarenes, but it has proved challenging to achieve in practice as shown by the limited number of existing protocols. Herein, we report on a highly general electrocatalytic strategy for the regioselective chlorination of various substituted heteroaryl scaffolds in an undivided cell setup, using ethyl chloroformate as the chlorine source. This strategy offers several practical advantages over existing methodologies, including an operationally simple experimental setup, exceptional functional group tolerance, and the possibility to form either the mono- or bis-chlorinated products in high selectivity depending on the choice of catalyst loading, electric current and ethyl chloroformate equivalents. The practicality and selectivity of the protocol were demonstrated by the successful chlorination of an array of densely-substituted arene frameworks as well as by the synthesis of chlorinated bioactive molecules.