Stereoselective and efficient chemical transformation of aldehydes and two molecules of pyrazolin-5-one into bis(spiropyrazolone)cyclopropanes under a column chromatography-free protocol at room temperature. - Elinson, Michail N.; Ryzhkova, Yuliya E.; Ryzhkov, Fedor V.; Kalashnikova, Varvara M.; Maslov, Oleg I. (Chemical Monthly / Monatshefte für Chemie, 2023)