Copper-mediated direct aryl C-H cyanation with azobisisobutyronitrile via a free-radical pathway.

An unprecedented protocol for the copper-mediated direct cyanation of aryl C-H by employing 2,2'-azobisisobutyronitrile (AIBN) as a free radical "CN" source is presented. The protocol not only provides a more efficient pathway for the synthesis of aryl nitriles in terms of the yields and the loading amount of copper salts but also, more importantly, represents a novel strategy for aryl C-H cyanation via a CN free-radical mechanism as compared to the CN anion-participating protocols often reported.