Site-Selective Electrochemical C-H Cyanation of Indoles.

An electrochemical approach for the site-selective C-H cyanation of indoles employing readily available TMSCN as cyano source has been developed. The electrosynthesis relies on the tris(4-bromophenyl)amine as a redox catalyst, which achieves better yield and regioselectivity. A variety of C2- and C3-cyanated indoles were obtained in satisfactory yields. The reactions are conducted in a simple undivided cell at room temperature and obviate the need for transition-metal reagent and chemical oxidant.