The Shi epoxidation is a chemical reaction

Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

 described as an asymmetric epoxidation of olefins with oxone (potassium peroxymonosulfate) and a fructose

Fructose

Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...

-derived catalyst (1).
This procedure generates epoxides with high enantiomeric excess

Enantiomeric excess

The enantiomeric excess of a substance is a measure of how pure it is. In this case, the impurity is the undesired enantiomer .-Definition:...

es from trans-disubstituted alkenes and trisubstituted alkenes. Cis-disubstituted alkenes and styrenes are asymmetrically epoxidized using a similar catalyst.