Synthesis of 1,2-fused indoles by radical cyclisation1

Abstract

Treatment of the 1-(ω-iodoalkyl)indole-3-carbaldehydes 8–13 with tributyltin hydride and AIBN results in radical cyclisation to give the 1,2-fused indoles 14–19 containing five-, six- and seven-membered rings. The tetrahydropyridoindole 18 is converted into the indolequinone 23.