Electrochemical C−H/N−H Functionalization for the Synthesis of Highly Functionalized (Aza)indoles

Indoles and azaindoles are among the most important heterocycles because of their prevalence in nature and their broad utility in pharmaceutical industry. Reported herein is an unprecedented noble‐metal‐ and oxidant‐free electrochemical method for the coupling of (hetero)arylamines with tethered alkynes to synthesize highly functionalized indoles, as well as the more challenging azaindoles. It's electric: An electrochemical coupling of (hetero)arylamines with tethered alkynes has been developed and provides highly chemo‐ and regioselective access to densely functionalized indoles and azaindoles. The electrochemical reaction employs ferrocene ([Cp2Fe]), an inexpensive organometallic reagent, as the redox catalyst and produces H2 as the only theoretical byproduct.