Ghashang, Majid, Mohammad Shafiee, Mohammad Reza, Hojati Najafabadi, Batool. Preparation of 1,5-diaryl-3-(arylamino)-1H-pyrrol- 2(5H)-one derivatives using 1-methylpiperidinium hydrogen sulfate as an efficient catalyst. Journal of the Iranian Chemical Research. 2012;5(2):65-71.