Synthesis of Indole from Aniline and Ethylene Glycol with Pb(II) Catalysts

Abstract Various catalysts for the direct synthesis of indole from ethylene glycol and aniline have been reported. It was found that in Pb(II) catalysts, the selectivities of indole are greatly influenced by the ligands; some of these, such as PbI2-KI and PbI2-BaI2, provide indole in high yields. The catalytic activities of lead halides and binary systems were investigated regarding the effects of the ligands of Pb(II); recycling of the catalyst was tested.