ChemInform Abstract: A Green Protocol for Asymmetric Epoxidation of Olefins Catalyzed by Carbon Dioxide Soluble Chiral Salen‐Mn(III) Complexes in Supercritical CO₂.

Abstract

2 . -Moderate enantioselectivity values are observed in the epoxidation reactions of several olefins under optimized conditions. The enantioselectivities are slightly improved when a more sterically hindered catalyst is used. Besides the green protocol, another important feature of this procedure is the stability of the epoxides under these conditions. The epoxidation of cis-β-methylstyrene (III) yields the cis-β-methylstyrene oxide (IV) with 47% enantiomeric excess. However, a large amount of trans-epoxide is also produced. -(GAO, C.; SHIN, W.; HAN, J.; HAN, D.; CHARI, M. A.; KIM, H.; AHN*, K.-H.; Bull. Korean Chem.

Organic carbonates as solvents in macrocyclic Mn(III) salen catalyzed asymmetric epoxidation of non-functionalized olefins

“…To make Mn(III) salen catalyst recyclable, strategies like its immobilization on organic polymers [5], inorganic supports [6][7][8], encapsulation in zeolite cavities [9], physical entrapment in siloxane membranes [10], tuneable solubility and multiphase methods have been reported. In the past, the ecologically sensible media have been used, notable among these are water [11][12][13], fluorinated hydrocarbons [14], supercritical CO 2 [15][16][17][18], and ionic liquids [19,20]. To our best knowledge there are no reports on the use of organic carbonates as solvent in asymmetric epoxidation reaction.…”