In the Mn-salen catalyzed asymmetric epoxidation of some olefins, non-linear relationship between reaction temperature and enantioselectivity was observed. For example, the epoxidation of 1, 3-cycloalkadiene with complex 3a as a catalyst showed the maximum enantioselectivity at 0° C. It was also found that the electronic nature of the aromatic substituent in the salen ligand affects enantioselectivity but its effect does not necessarily ...
[Matsushita, Mitsunori; Kamata, Keigo; Yamaguchi, Kazuya; Mizuno, Noritaka Journal of the American Chemical Society, 2005 , vol. 127, # 18 p. 6632 - 6640]