 Most commonly tributyltin hydride is utilized as the reducing agent, with azobisisobutyronitrile (AIBN) as a radical initiator.Triethylborane can also be used as a radical initiator.The reaction can begin with either an "ortho"-isocyanostyrene or a 2-alkenylthioanilide derivative, both forming the indole through Radical cyclization "via" an α-stannoimidoyl radical.