Due to the great importance of chiral compounds in the manufacture of drugs, vitamins, fragrances, and optical materials, the synthesis of chiral building blocks has attracted special attention. Chiral epoxides are among the most important intermediates that can react with a variety of reagents because of the polarity and ring-strain of the epoxide ring. Asymmetric epoxidation of olefins can convert prochiral olefins into epoxides with chiral carbon, which can be readily converted into various chiral compounds via regioselective ring-opening or functional group transformation reactions. Asymmetric synthesis reactions have been mainly induced by substrates or catalysts. The asymmetric synthesis induced by chiral catalysts is one of the most attractive and competitive areas in modern organic synthesis, because it can get a lot of new optical active substances using catalytic amount of chiral compounds. Asymmetric catalytic epoxidation of unfunctionalized olefins induced by the chiral catalyst has been the most effective way to obtain optical pure chiral epoxides. These chiral catalysts include enzymes, metal porphyrins, Salen-Mn (Ⅲ) complexs and organocatalysts. Among them, the synthesis of metal porphyrins and Salen-Mn (Ⅲ) complexs is inspired by enzymes. The organcatalyst, which does not contain metal ions, is regarded as a low pollution and lower toxicity catalyst. Asymmetric epoxidation of olefins catalyzed by these catalysts can get satisfactory yield and enantiomeric selectivity. Recent progress of enzymes, metal porphyrins, Salen-Mn (Ⅲ) complexs, and organcatalysts used for asymmetric epoxidation of olefins is reviewed. Moreover, the catalytic mechanisms and the development trend of this reaction are discussed.

Contents
1 Introduction
2 Enzyme-catalyzed asymmetric olefin epoxidation
2.1 Monooxygenases
2.2 Peroxidases
2.3 Artificial metalloenzymes
3 Metal porphyrin-catalyzed asymmetric epoxidation of unfunctionalized olefins
4 Salen-Mn (Ⅲ) complex-catalyzed asymmetric epoxidation of unfunctionalized olefins
4.1 Unsupported Salen-Mn(Ⅲ) complex-catalyzed asymmetric epoxidation of unfunctionalized olefins
4.2 Supported Salen-Mn(Ⅲ) complex-catalyzed asymmetric epoxidation of unfunctionalized olefins
4.3 Application of ionic liquid in Salen-Mn (Ⅲ) complex-catalyzed olefin asymmetric epoxidation
4.4 The mechanism of olefin asymmetric epoxidation catalyzed by Salen-Mn(Ⅲ) catalysts
5 Organic small molecule-catalyzed olefin asymmetric epoxidation
5.1 Chiral ketone-catalyzed olefin asymmetric epoxidation
5.2 Chiral iminium-catalyzed olefin asymmetric epoxidation