Synthesis of 1,8-dioxo-octahydroxanthenes and bis(indolyl)methanes catalyzed by [Et3NH][H2PO4] as a cheap and mild acidic ionic liquid

Triethyl ammonium dihydrogen phosphate was used as a cheap and mild acidic ionic liquid catalyst for synthesis of 1,8-dioxo-octahydroxanthenes and bis(indolyl)methanes. This methodology offers several advantages, such as good yields, short reaction times, simple procedure, and mild conditions.