General Features
The degree of enantioselectivity depends on numerous factors, namely the structure of the olefin, the nature of the axial donor ligand on the active oxomanganese species and the reaction temperature. Cyclic and acyclic (Z)-1,2-disubstituted olefins are epoxidized with almost 100% enantioselectivity whereas (E)-1,2-disubstituted olefins are poor substrates for Jacobsen's catalysts but yet give higher enantioselectivities when Katsuki's catalysts are used. Furthermore, the enantioselective epoxidation of conjugated dienes is much higher than that of the nonconjugated dienes.
The enantioselectivity is explained by either a "top-on" approach (Jacobsen) or by a "side-on" approach (Katsuki) of the olefin.
Read more about this topic: Jacobsen Epoxidation
Famous quotes containing the words general and/or features:
“Women born at the turn of the century have been conditioned not to speak openly of their wedding nights. Of other nights in bed with other men they speak not at all. Today a woman having bedded with a great general feels free to tell us that in bed the general could not present arms. Women of my generation would have spared the great general the revelation of this failure.”
—Jessamyn West (1907–1984)
“It is a tribute to the peculiar horror of contemporary life that it makes the worst features of earlier times—the stupefaction of the masses, the obsessed and driven lives of the bourgeoisie—seem attractive by comparison.”
—Christopher Lasch (b. 1932)