An Innovative Protocol for Synthesis of 5-Cyanoindole: A Key Ingredient for Antidepressant Drug Vilazodone Hydrochloride

The synthesis of 5-cyanoindole, a common intermediate employed in several synthetic routes of vilazodone hydrochloride, an antidepressant drug, is described in this work. Because it avoids the use of heavy metals and cyanide reagents, the strategy was more eco-friendly than previously documented approaches. The protocol is also robust and commercially viable. 96% of 5-cyanoindole was produced by the cyclization reaction, which was accomplished in the presence of Fe/AcOH. The current protocol is appropriate for large-scale preparation in industry.