Iron-catalyzed intramolecular reductive cyclization of o-nitroarenes to indoles under visible light irradiation

An efficient, mild and environmentally benign methodology for the synthesis of indoles via air stable, inexpensive Knölker complex catalyzed intramolecular reductive cyclization of o-nitrostyrenes at room temperature under photoirradiation has been developed. The stated methodology was capable for a diverse range of o-nitrostyrenes, generates outstanding yields of the indoles.