A Convenient Synthesis of α,α′-Bis(substituted benzylidene)cycloalkanones Catalyzed by Yb(OTf)3 Under Solvent-Free Conditions - Wang, Limin; Sheng, Jia; Tian, He; Han, Jianwei; Fan, Zhaoyu; Qian, Changtao (Synthesis, 2004)