WO2001081329A1

WO2001081329A1 - Method for the preparation of chiral epoxides

Info

Publication number: WO2001081329A1
Application number: PCT/KR2001/000658
Authority: WO
Inventors: Choong-Eui Song; Eun-Joo Roh
Original assignee: Korea Institute Of Science And Technology
Priority date: 2000-04-20
Filing date: 2001-04-20
Publication date: 2001-11-01
Also published as: AU2001252742A1

Abstract

The present invention relates to a method for the preparation of chiral epoxides, more particularly, to a method for preparing chiral epoxides by means of asymmetric epoxidation, comprising reacting olefins with oxidizing agents in the presence of one or more ionic liquids or mixture thereof with other organic solvents and chiral salen metallic catalysts. Such a method facilitates recovery and reuse of the expensive chiral salen metallic catalysts in which they maintain their activity and enantioselectivity such that chiral epoxides can be prepared in an economic manner.

Description

METHOD FOR THE PREPARATION OF CHIRAL EPOXIDES

TECHNICAL FIELD

The present invention relates to a method for the preparation of chiral epoxides, more particularly, to a method forpreparing chiral epoxides bymeans of asymmetric epoxidation, comprising reacting olefins withoxidizing agents in thepresence of one ormore ionic liquids ormixture thereof with other organic solvents and chiral salen metallic catalysts.

BACKGROUND ART

Asymmetric epoxidation of olefins in chiral salenmetallic catalysts has been widely used in the preparation of optically pure chiral epoxides as illustrated in scheme 1, and the obtained chiral epoxides have been also used as important intermediates in the synthesis of chiral compounds (E. N. Jacobsen, Asymmetric Catalytic Epoxidation of Unfunctionalized Olefins in Catalytic Asymmetric Synthesis (I. Ojima, Ed.), VCH, New York, Chapter 4.2, 1993; E. N. Jacobsen, M.H. Wu, Epoxida tion of Alkenes Other than Allylic Alcohols in Comprehensive Asymmetric Catalysis (II) ; E„ N. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.), Springer Verlag, Berlin Heidelberg, Chapter 18.2, 1999).

Scheme 1

wherein, A, B, C and D are substitutents of olefin and * means the chiral center.

Typical examples of chiral salen metallic catalysts for asymmetric epoxidation of olefins are Jacobsen' s salen catalyst disclosed in U.S. Pat. Nos. 5 663 393, 5 665 890 and 5 637 739; Katsuki's salen catalyst described in U.S. Pat. No. 5 599 957 issued to Y. N. Ito, T. Katsuki, Bull , Chem . Soc. Jpn . 1999, 72, 603; and pyrrolidine salen catalyst derived from homo-chiral pyrrolidine diamine proposed by C.E. Song et al . Chem . Commun . 2000, 615. Each of these catalysts has two enantiomers and can be used as a catalyst in the synthesis of chiral epoxides.through its reaction with olefin. However, there are limitations to performing asymmetric epoxidation using chiral salen metallic catalysts on a industrial scale due to high cost of catalysts.

To explore the possibility of the repetitive use of catalyst, several attempts to immobilize this type of catalyst have been made. Among these attempts, a fixation method was proposed: for example, by forming a covalent bond of chiral salen metallic catalysts to a non-soluble solid support; by physically entrapping them into a polydimethylsiloxane membrane; by steric occlusion in nano-sized cages of zeolites; by using a biphasic systems, and the like (B. B. De, B. B. Lohray, P. K. Dhal, Tetrahedron Lett . 1993, 34, 2371; B. B. De, B. B. Lohray, S. Sivaram, P. K. Dhal, Macromolecules 1994, 27, 2191; B. B. De, B. B. Lohray, S. Sivaram, P. K. Dhal, Tetrahedron : Asymmetry 1995, 6, 2105; B. B. De, B. B. Lohray, S. Sivaram, P. K. Dhal, J. Plym . Sci . , Polym . Chem . Ed. 1997, 35, 1809; F. Minutolo, D. Pimi, P. Savadori, Tetrahedron /Asymmetry 1996, 7, 2293; F. Minutolo, D. Pini, P. savadori, Tetrahedron Lett .1996, 37, 3375; L. Canali, E. Cowan, H. Deleuze, C. L. Gibson, D. C. Sherrington, Chem . Commun . 1998, 2561; G.-J. Kim, J.-H. Shin, Tetrahedron Lett . 1999, 40, 6827; M. J. Sabater, A. Corma, A. Domenech, ^'v. Fornes, H. Garcia, Chem . Commun . 1997, 1285; S. B. Ogunwumi, T. Bein, Chem . Commun . 1997, 901; M. D. Angelino, P. E. Ma cromolecules 1998, 22, 7581; I. F. J. Vankelecom, D. Tas, R. F. Parton, V. Van de Vyver, P. A. Jacobs, Angew. Chem . Int . Ed. Engl . 1996, 35, 1346; K. B. M. Janssen, I. Laquiere, W. Dehaen, R. F. Parton, I. F. J. Vankelecom, P. A. Jacobs, Tetrahedron : Asymmetr , 8, 3481; G. Pozzi, F. Cinato, F. Montanari, S. Quici, Chem . Commun . 1998, 877) . However, these methods did not give a sufficient enantioselectivity and actvity.

As an alternative, there was proposed a method comprising synthesizing a chiral monomer, followed by polymerizing it to a non-soluble polymer, as illustrated in scheme 2. The produced polymer can be used as a chiral salen catalyst in asymmetric epoxidation and, after reaction, it can be recovered and reused. However, this method also suffers from some disadvantages: difficulty in synthesizing an appropriate monomer and very poor optical selectivity. For these reasons, it also has a practical limitation { Tetrahedron Letters . 1996, 37(19), 3375).

Scheme 2

As described above, all the conventional methods afford much lower activity and enantioselectivity than homogeneous catalyst systems, because they need to modify the molecular structure of chiral salen catalysts. For this reason, they are not practical.

In view of the above circumstance, more practical process for recovering chiral catalyst still needs to overcome some problems of the conventional methods.

Meanwhile, salts that exist in liquid state under 100 °C are called "ionic liquids". They have specific vapor pressure of "~ 0" at room temperature, high solvation ability for various organic and inorganic material and very low coordination ability to metallic component. For these reasons, they are watched as next-generation alternative solvents that can overcome disadvantages of commercial organic solvents. Moreover, in these solvents, catalysts having polar or ionic character can be immobilized and thus the ionic liquid phase containing the catalyst can be easily separated from from non-polar reactants and/or products. Recent applications of ionic liquids in catalytic reactions include Friedel-Crafts reaction, Diels-Alder reaction, alkylation, olefin dimerization and oligomerization, hydrogenation, Heck reaction, hydroformylation, palladium catalyzed allylation and so forth (T. Welton, Chem . Rev. 1999, 99, 2071; K.R. Seddon,<_7. Chem . Tech . Biotechnol . 1997, 68, 351; and Y. Chauvin, CHEMTECH. H. Olivier) . But, up to now, they are not introduced and/or accomplished in asymmetric epoxidation of olefin.

In view of the above described problems, the present inventors have discovered and completed the present invention that, when asymmetric epoxidation of olefin with a oxidizing agent was performed in the presence of one or more ionic liquids and/or mixture thereof with other solvents and a chiral salen metallic catalyst, the chiral salen metallic catalyst can be immobilized in the ionic liquids and it can be easily separated from the non-polar reactants and products. Thus, the expensive chiral salen catalyst can be easily recovered. It is also found that the recovered catalyst maintains its activity and enantioselectivity and can be reused in the further reaction, and thus, chiral epoxide can be synthesized in an economicmanner .

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an economic and improved method for preparing chiral epoxides by asymmetric epoxidation.

Still another obj ect of the present invention is to provide a method for recovering a chiral salen metallic catalyst by immobilizing such catalyst in ionic liquids.

To achieve the above objects, there is provided a method for the preparation of chiral epoxides, more particularly, a method for preparing chiral epoxides by means of asymmetric epoxidation, comprising reacting olefins with oxidizing agents in the presence of one or more ionic liquids or a mixture thereof with other solvents and chiral salen metallic catalysts.

The above objects and other features and advantages of the present invention will become more apparent from the following detailed description. A preferred embodiment of the present invention will now be described with reference to specific embodiment examples.

DISCLOSURE OF THE INVENTION

The present invention relates to a method for the preparation of chiral epoxides, more particularly, to a method forpreparing chiral epoxides bymeans of asymmetric epoxidation, comprising reacting olefins with oxidizing agents in the presence of one ormore ionic liquids ormixture thereof with other solvents and one or more chiral salen metallic catalysts.

1. Ionic liquid

Ionic liquid may be added solely, with different ionic liquids and/or in combination with other common organic solvents such as methylene chloride, chlorobenzene, benzene, andthelike.

Suitable ionic liquid of the present invention is preferably imidazolium salt having formula 1;

(formula 1)

wherein, R¹ and R³ are independently alkyl group; R², R⁴ and R⁵ are independently hydrogen or alkyl group; n is an integer from 1 to 3; and A^" means anion capable of forming salt.

Preferably, R², R⁴ and R⁵ are hydrogen, R¹ and R³ are independently Ci-Cβ primary, secondary or tertiary alkyl, more preferably, R¹ is C₁-C₃ alkyl and R³ is C₃-C₈ alkyl, or R¹ is C₃-C₈ alkyl and R³ is C1-C3 alkyl.

Preferably, A^" is MX_k ^~ or R0^~, wherein M is selected from the group consisting of Group VIII, IB, 2B, IIIA, IVA and VA in the periodic table of Elements (CAS version) ; X represents halogen atom, preferably, fluorine, R is selected from the group consisting of alkyl sulfonyl, haloalkyl sulfonyl, phosphoryl and carbonyl group, and k is 2-6.

Particular examples of the ionic liquid include, but are not necessarily limited to, salts of l-ethyl-3-methyl-imidazolium(EMIM) , l-methyl-3-propyl-imidazolium(PMIM) , l-butyl-3-methyl-imidazolium(BMIM) , l-methyl-3-pentyl-imidazolium(PMIM) , l-hexyl-3-methyl-imidazolium(HMIM) , l-heρtyl-3-methyl-imidazolium with anion such as hexafluoroanitimonate (SbFε) , hexafluorophosphate (PFβ) , tetrafluoroborate (BF₄) , trifluoromethansulfonate (OTf) , acetate (OAc) , and the like. As illustrated above, ionic liquid having formula 1 has been received much attention as a alternative for common organic solvents because it is stable against air and moisture and has other various benefits described above (See T. elton, Chem . Rev. , 1999, 99, 2071; K.R. Seddon, J. Chem . Tech . Biotechnol . 1997, 68, 351; Y. Chauvin, H. Olivier, CHETECH. 1995, 26) .

Such an ionic liquid is environment-friendly and has good physical and chemical properties for solvent such as non-volatility, non-inflammability and thermal stability and high solvation ability. Additionally, the ionic liquid is suitable for catalytic reaction due to its very low coordination ability to metal. In particular, polar or ionic catalysts such as chiral salen metallic catalyst can be easily immobilized within the ionic liquid such that they can be easily separated from reactants and the resulted products.

Solvation ability of the salt having formula 1 depends on substituents of the imidazoliummoiety and anionic structure . For instance, whereas PFε or SbFβ salt as one example of l-butyl-3-methylimidazolium salts is hydrophobic to be immiscible with water as well as with saturated hydrocarbon, benzene and dialkyl ether, BF or TfO salt as an another example has a hydrophilic property. The salts of formula 1 used in the present invention can be appropriately selected regarding the reaction conditions such as the oxidizing agent, the solvent system, etc. For example, when asymmetric epoxidation of olefins is performed in aqueous solution containing NaOCl, the water-insoluble imidazolium salts are more preferable since the salts facilitate the recoveryof chiral catalysts . Specifically, when l-butyl-3-methylimidazolium salts are used as a solvent, ΕF or SbF₆ ^" is most preferable as A^" moiety.

2. Chiral salen metallic catalysts

Suitable chiral salen metallic catalysts used in the preparationof chiral epoxides accordingto thepresent invention include all of commercially available and typical chiral salen metallic catalysts [See E. N. Jacobsen, Asymmetric Catalytic Epoxidation of Unfunctionalized Olefins in Ca talytic Asymmetric Syn thesis ( I. Ojima, Ed.), VCH, New York, Chapter 4.2, 1993; E.N. Jacobsen, M.H. Wu, Epoxidation of Alkenes Other than Allylic Alcohols in Comprehensive Asymmetric Catalysis (II) ; E.N. Jacobsen, A. PfaltzH. Yamamoto (Eds.), Springer Verlag, Berlin Heidelberg, Chapter 18.2, 1999; U.S. Pat. No.5,637,739(1997); U.S. Pat. No. 5,663,393(1997); U.S. Pat. No. 5,420,314(1995); U.S. Pat. No. 5,599,957(1997); International published applications WO93/03838; WO94/03271 (1994 ) ; U.S. Pat. No. 5,352,814(1994); U.S. Pat. No. 5,639,889(1997); and U.S. Pat. No. 5,916,975(1995)]. Since all these chiral salen metallic complexes act as catalysts under substantially the same conditions such as reaction solvent, a oxidizing agent, reaction temperature and so on, imidazolium salts of the present invention are very efficiently used together with all of typical chiral salen metallic salts.

Particular examples of chiral salen metallic catalyst used in the present invention are illustrated below:

1) the first embodiment example of such chiral salen metallic catalyst has following formula 2 :

( formula 2 )

wherein, R¹, R², R³ and R⁴ are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group; or R¹, R², R³ and R⁴ can be bonded each other to form Cx-Cs rings. X¹, X², X³, X⁴, X⁵, X⁶, X⁷ and X⁸ are independently hydrogen, halogen, alkyl, silyl, silyloxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, imino, amido, phosphoryl, carbonyl or sulfonyl group. Y¹ and Y² are independently hydrogen or alkyl group. M represents transition metal, preferably Mn, Cr, Fe, Co, Ti, V, Ru or Os, more preferablyMn, andArepresents anion, preferably Cl, CH₃COO, PF₆, BF₄ or SbF₆ .

Awide varietyof catalysts of formula 2 has been synthesized and used in the synthesis of chiral epoxides [See Jacobsen et al., J. Am . Chem . Soc , 1991, 113, 7063; Jacobsen et al . , Tetrahedron Letters, 1995, 35, 5123, 5457] . The examples thereof are as follows:

Among the compounds of formula 2, preferred embodiment has formula 2a;

(formula 2a)

wherein hydrogen atoms 1 and 2 together are in trans positions; R represents primary, secondary or tertiary alkyl group having 1 to 4 carbon atoms, halogen group, alkoxy or trialkylsilyloxy group -O-SiR^R³, wherein R^R² and R³ are independently alkyl group having 1 to 4 carbon atoms; and A is Cl, CH₃COO, PF_6/ BF or SbF₆.

More preferred chiral salen metallic catalysts of the above formula 2a are the compound of formula 2b or 2c. (formula 2b)

( formula 2c)

An another embodiment of the chiral salenmetallic catalysts is the compound having formula 2d; (formula 2d)

In formula 2d, hydrogen atoms 1 and 2 together are in trans positions; R represents primary, secondary or tertiary alkyl group having 1 to 4 carbon atoms, halogen group, alkoxy or trialkylsilyloxy group -O-SiR^R³, wherein R^R² and R³ of alkyl group having 1 to 4 carbon atoms; and A is Cl, CH₃CO0, PF₆, BF₄ or SbF₆.

More preferred compounds of the above formula 2d are formula 2e or 2f:

(formula 2e)

( formula 2 f )

2) the second embodiment example of such chiral salen metallic catalyst has the following formula 3: (formula 3)

wherein R¹, R², R³ and R⁴ are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group; or R¹, R², R³ and R⁴ can be bonded each other to form C-Cs rings. X¹, X², X³, X⁴, X⁵ and X⁶ are independently hydrogen, halogen, alkyl, silyl, silyloxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, imino, a ido, phosphoryl, carbonyl or sulfonyl group; or X¹ and X², X⁴ and X⁵ can be bonded each other to form benzene ring. R⁵, R⁶, R⁷ andR⁸ are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group; or R⁶ and X¹, R⁸ and X⁴ can be bonded each other to form C₅-C₆ ring. Y¹ and Y² are independently hydrogen or alkyl group. M represents transition metal, preferably Mn, Cr, Fe, Co, Ti, V, Ru or Os, more preferablyMn, andArepresents anion, preferably Cl, CH₃COO, PF₆, BF₄ or SbF₆.

Among chiral salen metallic catalysts of the above formula 3, more preferred ones are the compound of formula 3a or 3b, for example Katsuki's Catalyst as disclosed in U.S. Pat. No. 5,420,314(1995); U.S. Pat. No. 5,599,957(1997); U.S. Pat. No. 5,352,814(1994); and U.S. Pat. No. 5,639,889(1997). (formula 3a)

In formula 3a, hydrogen atoms 1 and 2 together are in trans positions; R¹ represents hydrogen or methyl group; R² represents methyl or phenyl group, preferably phenyl group; and A is anion, preferably Cl, CH₃COO, PF₆, BF₄ or SbF₆.

(formula 3b)

In formula 3b, hydrogen atoms 1 and 2 together are in trans positions; R¹ represents hydrogen or methyl group; R² represents methyl, ethyl or propyl group; R³ represents hydrogen, methyl or ethyl group; R² andR³ represent independently methylene group and can be bonded each other to form C₅ ring; and A is anion, preferably Cl, CH₃COO, PF₆, BF₄ or SbF₆.

3) the third embodiment example of such chiral salen metallic catalyst has the following formula 4: (formula 4)

wherein R¹ and R² are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group; B represents hetero compound and including oxygen, NR,S, sulfone and sulfoxide; R represents alkyl, aryl, alkylcarbonyl, arylcarbonyl, alkylsulfonyl and arylsofonyl; n is 1 to 3; X¹, X², X³, X⁴, X⁵, X⁶, X⁷ and X⁸ are independently hydrogen, halogen, alkyl, silyl, silyloxy alkoxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, i ino, amido, phosphoryl, carbonyl or sulfonyl group; Y¹ and Y² are independently hydrogen and alkyl group; M represents transition metal, preferably Mn, Cr, Fe, Co, Ti, V, Ru orOs, more preferablyMn; andArepresents anion, preferably Cl, CH₃C00, PF₆, BF₄ or SbF₅.

Typical examples of the chiral salen metallic catalyst of the above formula 4 are illustrate belo [U.S. Pat. No. 5,916,975(1999); Song et al . , Chem . Commun . 2000, 615].

wherein R is primary, secondary or tertiary alkyl, cycloalkyl, aryl or substituted aryl group.

From chiral salen metallic catalysts of the above formula 4, more preferred ones has the compound of formula 4a or 4b, as shown below; ( formula 4 a )

In formula 4a, hydrogen atoms 1 and 2 together are in trans positions; R¹ represents primary, secondary or tertiary alkyl group, cycloalkyl group, aryl group or heteroaryl group; R² represents primary, secondary or tertiary group having 1 to 4 carbon atoms, halogen group, alkoxy having 1 to 4 carbon atoms; or trialkylsilyloxy group -0-SiR¹R²R³, wherein R^R² and R³ are independently alkyl group having 1 to 4 carbon atoms; X presents methylene group (-CH₂-) , carbonyl group (-CO-) or carboxyl group

(-COO-); and A is Cl, CH₃COO, PF₆, BF₄ or SbF_δ

Most preferred chiral salenmetallic catalysts of the above formula 4a are the compounds of the following formula 4b or 4c; (formula 4b)

In formula 4b, R is primary, secondary or tertiary alkyl, cycloalkyl, aryl or heteroaryl group; X represents methylene group (-CH₂-) , carbonyl group (-CO-) or carboxyl group (-C00-) . (formula 4c)

In formula 4c, R is primary, secondary or tertiary alkyl, cycloalkyl, aryl or heteroaryl group; X represents methylene group (-CH₂-) , carbonyl group (-CO-) or carboxyl group (-C00-) .

An another example of the compound of formula 4 is the

compound of formula 4d; (formula 4d)

In formula 4d, hydrogen atoms 1 and 2 together are in trans positions; R represents primary, secondary or tertiary alkyl group, halogen group, alkoxy having 1 to 4 carbon atoms; or trialkylsilyloxy group -0-SiR¹R²R³, wherein R^X,R² and R³ of are independently alkyl group having 1 to 4 carbon atoms; and A is Cl, CH₃COO, PF₅, BF₄ or SbF₆

Most preferred chiral salenmetallic catalysts of the above formula 4d are the compounds of the following formula 4e or 4f ; (formula 4e)

4) the forth embodiment example of such chiral salen metallic catalyst has the following formula 5: (formula 5)

wherein X¹, X², X³, X⁴, X⁵, X⁶, X⁷ and X⁸ are independently hydrogen, halogen, alkyl, silyl, silyloxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, imino, amido, phosphoryl, carbonyl or sulfonyl group; Y¹ and Y² are independently hydrogen and alkyl group; Z¹, Z², Z³ and Z⁴ are independently hydrogen, alkyl, halogen, cyano or nitro group; ; M represents transitionmetal, preferably Mn, Cr, Fe, Co, Ti, V, RuorOs, more preferablyMn; andA represents anion, preferably Cl, CH₃COO, PF₆, BF₄ or SbF₅. Preferred examples of the chiral salen metallic catalyst of the above formula 5 are ones having the formula 5a; (formula 5a)

In formula 5a, R represents primary, secondary or tertiary alkyl group having 1 to 4 carbon atoms, halogen group, alkoxy or trialkylsilyloxy group -0-SiR¹R²R³, wherein R^R² and R³ are independently alkyl group having 1 to 4 carbon atoms; and A is Cl, CH₃COO, PF₆, BF₄ or SbF₆.

In another aspect of the present invention, asymmetric epoxidation as defined in scheme 1 proceeds by adding alkene and chiral salen metallic catalyst into one or more imidazolium salt or mixed solvent system there of with other organic solvents and then additionally adding oxidizing agents to this solution such that asymmetric epoxidation takes place. Preferred oxidizing agents include, but are not necessarily limited to, NaOCl, m-chloroperbenzoic acid, iodosylbenzene (PhlO) , sodium periodate (NaI0₄) , tetrabutylammonium periodate (Bu₄NI0₄) . In particular, NaOCl is more preferred because of its economical benefit .

II . Recovery of chiral salen metallic catalyst

The present invention provides a method of recovering chiral salen metallic catalyst by immobilization process which comprises fixing chiral salen metallic catalyst in ionic liquid after reaction. More particularly, the method of recovering chiral salen metallic catalyst from the reaction mixture obtained by asymmetric epoxidation of olefin with oxidizing agents comprises the step of; a) performing asymmetric epoxidation of olefin in the presence of chiral salen metallic catalyst and one or more ionic liquids of formula 1 or the mixture thereof with other organic solvent; b) separating the organic layer from the reaction mixture anddistilling volatile solvent to obtain a concentratedresidue; c) adding organic solvent which is notimmiscible with ionic liquid to the residue to form two separated layers, wherein the one is an organic layer and the other is an ionic liquid layer; and, d) separating the ionic liquid layer from the two separated layers to obtain the ionic liquid solution comprising the chiral catalyst.

In the first step, olefin is asymmetrically epoxized by a oxidizing agent in the presence of chiral salen metallic catalysts and one or more ionic liquids or mixture thereof with other organic solvents such as methylenechloride, chlorobenzene, benzene and the like. The first step can be performed under the previously known reaction conditions except that one or more ionic liquids or mixture there of with other organic solvents are used instead of conventional organic solvents.

In the second step, the organic layer obtained from the first step is separated and treated with ordinary work-up process . For instance, the work-up process includes washing the organic layer with saline water, drying with a drying agent such as magnesium sulfate, filtering and distilling volatile solvent under vacuum or reduced pressure. And the work-up process may be varied depending on types and chemical or physical properties of the product.

In the third step, two separated layers are obtained by adding organic solvent to the residue obtained in step 2. The upper layer normally contains non polar reactants and products, and the bottom layer contains chiral catalyst immobilized in the ionic liquid. Organic solvent used in the extraction process should be immiscible with the ionic liquid while dissolving chiral epoxide. As a preferable example, hexane, benzene, chlorobenzene, diethylether, isopropanol, and the like can be mentioned. Furthermore, extraction can be effectively performed by agitation. In addition, in case where boiling point of the chiral epoxide obtained from the third step is low, the concentrated residue of the second step may be directly distilled to remove the chiral epoxide from the chiral salen metallic catalyst immobilized within the ionic liquid.

Finally, the ionic liquid solution comprising the chiral catalyst can be separated from the two separated layers . The ionic liquid solution comprising the chiral catalyst can be reused in the synthesis of the chiral epoxides without any further purification.

Meanwhile, from upper organic layer, chiral epoxide can be isolated and purified by ordinary method such as column chromatography, distillation or recrystallization and so on to produce a purified chiral epoxide.

As described in the foregoing specification, it will be appreciated that the present invention is effective to produce chiral epoxides by asymmetric epoxidation, comprising reacting olefin with oxidizing agent in the presence of one or more ionic liquids or mixture there of with other organic solvents and this method also facilitates recovery and reuse of valuable chiral catalysts. Futher, the ionic liquid also reduces the reaction time and permits to prepare a chiral epoxides with high yield and optical purity, compared with the conventional asymmetric epoxidation without such a ionic liquid. And these would be more fully appreciated by the following Examples .

Example 1 - Preparation of chiral epoxide and recovery of chiral catalyst 1

To a solvent mixture of 30 ml of methylene chloride and 7.5 ml of PF₆ salt of 3-butyl-l-methyl imidazolium, 2, 2-dimethylchromene (5.0 g, 31.3 mmol) and (R, R) -catalyst having the formula 2b (0.79 g, 1.25 mmol) were added. NaOCl used as a oxidizing agent was CLOROX, commercial household bleach. Such a agent became buffer solution by adding desired amount of Na₂HP0₄ in a volume ratio of CLOROX : 0.05M Na₂HP0₄ of about 2.5:1 and controlled its pH value to 11.3 by adding a small amount of IN NaOH dropwise (See N.H.Lee, A.R. Muci, E.N. Jacobsen, Tetrahedron Lett . 1991, 32, 5055.)

The obtained NaOCl solution was allowed to cool to 0 °C and then added to the imidazolium solution. The reaction solution was stirred while maintaining its internal temperature at 0 °C and observed the completion of the reaction with thin layer chromatography. After 1.5 hours, the reaction was completed.

After reaction, the organic layer was separated from the reaction mixture and washed with saturated NaCl solution, and then concentrated under reduced pressure to eliminate volatile solvent .

To the obtained residue, n-hexane was added, and the hexane layerwas separatedandthen concentratedunder reducedpressure . The obtained residue was separated and purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral epoxide with 86% yield and 96% ee optical purity. A pure chiral epoxide was obtained via chiral high-pressure liquid chromatography (HPLC) ; seperation condition; Daicel Chiralpak AD, 2-propanol/n-hexane (5/95) , the flow rate 0.8 ml/min, 9.30 min(3R, 4R) , 10.63 min(3S, 4S) .

The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by

Mn-analysis showing that (R, R) -catalyst having formula 2b exists in the bottom layer.

Example 2 - Preparation of chiral epoxide and recovery of chiral catalyst 2

To a solvent mixture of 30 ml of chlorobenzene and 7.5 ml of PF_δ salt of 3-butyl-l-methyl imidazolium, 2, 2-dimethylchromene (5.0 g, 31.3 mmol) and (R, R) -catalyst having the formula 2b (0.79 g, 1.25 mmol) were added. NaOCl

solution (110 ml) was allowed to cool to 0 ^°C and then added to this solution. The reaction solution was stirred while

maintaining its internal temperature at 0 ^°C and observed the completion of the reaction with thin layer chromatography. After 1.5 hours, the reaction was completed.

After reaction, the organic layer was separated from the reaction mixture and washed with saturated NaCl solution, and then concentrated under reduced pressure to eliminate volatile solvent.

To the obtained residue, n-hexane was added, and the hexane

^' layerwas separated andthen concentratedunder reducedpressure . The obtained residue was separated and purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine

= 10 : 1 : 0.01) to give the chiral epoxide with 80% yield and

94% ee optical purity.

The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by Mn-analysis showing that (R, R) -catalyst having formula 2b exists in the bottom layer.

Example 3 - Preparation of chiral epoxide and recovery of chiral catalyst 3

Except that SbFε salt was used instead of PFe salt, the reaction was performed in the same manner as described in Example

2, to obtained the desired chiral epoxide with 82% yield and 95% ee optical purity. The catalyst used was recovered as fixed in ionic liquid and the existence thereof is checked.

Example 4 - Preparation of chiral epoxide and recovery of chiral catalyst 4 To a solvent mixture of 1 ml of methylene chloride and 0.25 ml of PF₆ salt of 3-butyl-l-methyl imidazolium, 6-cyano-2, 2-dimethylchromene (100 mg, 0.54 mmol) and (R, R) -catalyst having the formula 2b (13.7 mg, 0.02 mmol) were added. NaOCl solution (2.1 ml) was allowed to cool to 0 ^°C and then added to this solution. The reaction solution was stirred

while maintaining its internal temperature at 0 ^°C and observed the completion of the reaction with thin layer chromatography. After 4 hours, the reaction was completed.

To the obtained residue, n-hexane was added, and the hexane layer was separatedandthenconcentratedunder reducedpressure . The obtained residue was purified with column chromatography

(eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral product with 72% yield and 94% ee optical purity. A pure chiral epoxide was obtained via chiral high-pressure liquid chromatograph (HPLC) ; seperation condition; Daicel Chiralcel OJ, 2-propanol/n-hexane (30/70) , the flow rate 1 ml/min, 13.95 min (3R, 4R) , 26.88 min (3S, 4S).

The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by Mn-analysis showing that (R,R) -catalyst having formula 2b exists in the bottom layer.

Example 5 - Preparation of chiral epoxide and recovery of chiral catalyst 5 To a solvent mixture of 1 ml of chlorobenzene and 0.25 ml of PF₆ salt of 3-butyl-l-methyl imidazolium, 6-cyano-2, 2-dimethylchromene (100 mg, 0.54 mmol) and (R,R) -catalyst having the formula 2b (3.7 g, 0.02 mmol) were added.

NaOCl solution (21 ml) was allowed to cool to 0 ^°C and then added to this solution. The reaction solution was stirred while

maintaining its internal temperature at 0 ^°C and observed the completion of the reaction with thin layer chromatography. After 4 hours, the reaction was completed.

To the obtained residue , n-hexane was added, and the hexane layerwas separatedandthe concentratedunder reducedpressure. The obtained residue was separated and purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 60 : 1 : 0.01) to give the chiral epoxide with 77% yield and 87% ee optical purity The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by Mn-analysis showing that (R, R) -catalyst having formula 2b exists in the bottom layer.

Example 6 - Preparation of chiral epoxide and recovery of chiral catalyst 6

Except that SbFε salt was used instead of PF_δ salt, the reaction was performed in the same manner as described in Example

4, to obtained the chiral epoxide with 78% yield and 91% ee optical purity. The catalyst used was recovered as fixed in ionic liquid and the existence thereof is checked.

Example 7 - Preparation of chiral epoxide and recovery of chiral catalyst 7 To a solvent mixture of 1 ml of methylene chloride and 0.25 ml of PFβ salt of 3-butyl-l-methyl imidazolium, indene(100 mg, 0.86 mmol) and (R,R) -catalyst having the formula 2b (22 mg, 0.03 mmol) were added. NaOCl solution (3.1 ml) was allowed to

cool to 0 ^°C and then added to this solution. The reaction solution was stirred while maintaining its internal temperature at 0 °C and observed the completion of the reaction with thin layer chromatography. After 4 hours, the reaction was completed. After reaction, the organic layer was separated from the reaction mixture and washed with saturated NaCl solution, and then concentrated under reduced pressure to eliminate volatile solvent .

To the obtained residue, n-hexane was added, and the hexane layerwas separatedandthen concentratedunder reducedpressure . The obtained residue was separated and purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral epoxide with 72% yield and 84% ee optical purity. The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by Mn-analysis showing that (R, R) -catalyst having formula 2b exists in the bottom layer. Example 8 - Preparation of chiral epoxide and recovery of chiral catalyst 8

To a solvent mixture of 1 ml of chlorobenzene and 0.25 ml of PF₆ salt of 3-butyl-l-methyl imidazolium, indene(100 mg, 0.86 mmol) and (R,R) -catalyst having the formula 2b (22 mg, 0.03 mmol) were added. NaOCl solution (3.1 ml) was allowed to cool

to 0 ^°C and then added to this solution. The reaction solution was stirred while maintaining its internal temperature at 0 ^°C and observed the completion of the reaction with thin layer chromatography. After 4 hours, the reaction was completed. After reaction, the organic layer was separated from the reaction mixture and washed with saturated NaCl solution, and then concentrated under reduced pressure to eliminate volatile solvent . To the obtained residue, n-hexane was added, and the hexane layerwas separated andthenconcentratedunder reducedpressure. The obtained residue was separated and purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral epoxide with 58% yield and 82% ee optical purity.

The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by Mn-analysis showing that (R, R) -catalyst having formula 2b exists in the bottom layer. Example 9 - Preparation of chiral epoxide and recovery of chiral catalyst 9

To a solvent mixture of 1 ml of methylene chloride and 0.25 ml of PFε salt of 3-butyl-l-methyl imidazolium, cis-β-methylstyrene (100 mg, 0.85 mmol) and (R, R) -catalyst having the formula 2b (21.5 mg, 0.034 mmol) were added. NaOCl

solution (3.0 ml) was allowed to cool to 0 ^°C and then added to this solution. The reaction solution was stirred while maintaining its internal temperature at 0 ^°C and observed the completion of the reaction with thin layer chromatography.

After 3 hours, the reaction was completed.

To the obtained residue, n-hexane was added, and the hexane layer was separatedand then concentratedunder reducedpressure .

The obtained residue was purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral epoxide with 72% yield of cis/trans (3.7 :

1) and 86% ee optical purity. The separation of the chiral epoxide was performed by the same manner as described in J. Org .

Chem. 1991, 56, 2996. The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by Mn-analysis showing that (R, R) -catalyst having formula 2b exists in the bottom layer.

Example 10 - Preparation of chiral epoxide and recovery of chiral catalyst 10

To a solvent mixture of 1 ml of chlorobenzen and 0.25 ml of PF₆ salt of 3-butyl-l-methyl imidazolium, cis-β-methylstyrene (100 mg, 0.85 mmol) and (R,R) -catalyst having the formula 2b (21.5 g, 0.034 mmol) were added. NaOCl solution (3.0 ml) was used as a oxidizing agent, as described

Example l,was allowed to cool to 0 ^°C and then added to this solution. The reaction solution was stirred while maintaining its internal temperature at 0 ^°C and observed the completion of the reaction with thin layer chromatography. After 3 hours, the reaction was completed.

To the obtained residue, n-hexane was added, and the hexane layerwas separatedand then concentratedunder reducedpressure. The obtained residue was separated and purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral epoxide with 68% yield of cis/trans (2.5:1) and 83% ee optical purity. In the same manner as described the Example 9, the obtained chiral epoxide was seperated.

Example 11 - Preparation of chiral epoxide and recovery of chiral catalyst 11

To a solvent mixture of 1 ml of methylene chloride and 0.25 ml of PF_δ salt of 3-butyl-l-methyl imidazolium, 1-phenylcyclohexene (100 mg, 0.63 mmol) and (R, R) -catalyst having the formula 2b (16 mg, 0.025 mmol) were added. NaOCl

solution (3.0 ml) was allowed to cool to 0 ^°C and then added to this solution. The reaction solution was stirred while

To the obtained residue, n-hexane was added, and the hexane layerwas separatedandthen concentratedunder reducedpressure . The obtained residue was separated and purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral epoxide with 77% yield and 84% ee optical purity. The separation of the obtained chiral epoxide was performed by the same manner as described in J. Org. Chem . 1991, 56, 2996. The chiral catalyst was recovered from the bottom layer comprising the catalyst and imidazolium salt, and tested by Mn-analysis showing that (R, R) -catalyst having formula 2b exists in the bottom layer.

Example 12 - Preparation of chiral epoxide and recovery of chiral catalyst 12

To a solvent mixture of 1 ml of chlorobenzene and 0.25 ml of PF₆ salt of 3-butyl-l-methyl imidazolium, 1-phenylcyclohexene (100 mg, 0.63 mmol) and (R,R) -catalyst having the formula 2b (16 mg, 0.025 mmol) were added. NaOCl solution (2.3 ml) was allowed to cool to 0 °C and then added to this solution. The reaction solution was stirred while

To the obtained residue, n-hexane was added, and the hexane layerwas separatedand then concentrated under reducedpressure . The obtained residue was purified with column chromatography (eluent; n-Hexane : ethylacetate : triethylamine = 10 : 1 : 0.01) to give the chiral epoxide with 66% yield and 83% ee optical purity. The obtained chiral epoxide was seperated in the same manner as described Example 11.

Example 13- Preparation of chiral epoxide and recovery of chiral catalyst 13 The desired chiral epoxide was obtained as the same manner in Example 4, except for using (S, S) -catalyst having the formula 2b as a catalyst. The used catalyst was separated, recovered and observed the existence and chiral activity. The obtained chiral epoxide had 86% yield and 97% ee optical purity. Example 14 - Preparation of chiral epoxide and recovery of chiral catalyst 14

The desired chiral epoxide was obtained as the same manner in Example 4, except for using (S, S) -catalyst having the formula

2c as a catalyst. The obtained chiral epoxide had 81% yield and

94% ee optical purity. The catalyst was separated and recovered, and the existence was checked.

Example 15 - Preparation of chiral epoxide and recovery of chiral catalyst 15

The desired chiral epoxide was obtained as the same manner in Example 4, except for using (R,R) -catalyst having the formula

4b (X=C0, R=CH₃) as a catalyst. The obtained chiral epoxide had 90% yield and 94% ee optical purity. The catalyst was separated and recovered, and the existence was checked.

Example 16 - Preparation of chiral epoxide and recover of chiral catalyst 16 The desired chiral epoxide was obtained by epoxidation for 5 hr as the same manner in Example 4, except for using (R, R) -catalyst having the formula 4b as a catalyst . The obtained chiral epoxide had 87% yield and 89% ee optical purity. The catalyst was separated and recovered, and the existence was checked.

(Table 1)

a : [bmim] [PF₆] is PF₆ salt of 3-butyl-l-methylimidazolium

[bmim] [SbF₆] is SbF₆ salt of 3-butyl-l-methylimidazolium b : analysis by chiral chromatography or chiral HPLC c : cis : trans selectivity d : for the formula 4b, X=CO and R=CH₃ catalyst

As described in the above Table 1, the results indicate that the asymmetric epoxidation of olefin according to the present invention has significantly reduced reaction time, as compared with conventional epoxidation reaction . Specifically, in case 2 , 2-dimethylchromene is asymmetrically epoxidized in a solvent system without such an ionic liquid, it is expected to take about 9 hours to complete the reaction, whereas the epoxidation in a solvent system containing one or more ionic liquids requires only about 1.5 hours . Moreover, by the process of the present invention it is possible to produce chiral epoxide with high-yield and optical purity .

Example 17 - Evaluation of the reuse of the recovered chiral catalyst

In order to evaluate the activity and optical selectivity of the recovered chiral salen metallic catalyst, epoxidation reaction was performed in the same manner in Example 1, except that the recovered catalyst was used instead of fresh catalyst. Yields and optical purity of the epoxy compounds are summarized in Table 2. As shown in Table 2, even the 5 times recovered catalyst exhibited almost the same results with the fresh catalyst. Thus, it is found that it is possible to reuse the recovered catalyst in the asymmetric epoxidation of olefin, as its fixed state in the ionic liquid and the recovered catalyst gave still high-yield and optical purity of costly chiral epoxide .

(Table 2) yield and optical purity of recovered chiral epoxide

As described above, the improved and economical process for preparing chiral epoxides of the present invention has been accomplishedbyasymmetric epoxidation of olefins with oxidizing agents in the presence of chiral salen metallic catalyst and one or more ionic liquids or mixture thereof with other organic solvents and ensures more simple and convenient recovery of costly chiral salen catalysts after the epoxidation, as compared with prior known methods, so that the recovered catalyst can be repeatedly used in future process.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims .

Claims

WHAT IS CLAIMED IS:

1. A method for preparing chiral epoxide by asymmetric epoxidation of olefin, comprising reacting olefin with an oxidizing agent in the presence of chiral salen metallic catalyst and one or more imidazolium salts having formula 1 or mixture thereof with other organic solvent: (Formula 1)

wherein R¹ and R³ are independently alkyl group; R², R⁴ and R⁵ are independently hydrogen or alkyl group; n is an integer from about 1 to 3; and A^" means anion capable of forming salt.

2. The method according to claim 1, wherein R , R and R are hydrogen, R¹ and R³ are independently Cι~Cs alkyl group, A^~ is MX_k ^~ or RO^", wherein M is selected from the group consisting of VIII, IB, 2B, IIIA, IVA and VA elements in periodic table of elements (CAS version) and X represents halogen atom, R is selected from group consisting of alkyl sulfonyl, haloalkyl sulfonyl, phosphonyl and cabonyl group, and k is an integer of 2-6.

3. The method according to claim 1, wherein R¹ represents Cι~C₃ alkyl and R³ represents C₃~C₈ alkyl, or R¹ represents Cι~C₃ alkyl and R³ represents Cι~C₃ alkyl.

4. The method according to claim 1, wherein the imidazolium salts is selected from the group consisting of salts of l-ethyl-3-methyl-imidazolium(EMIM) , l-methyl-3-propyl-imidazolium ( PMIM) , l-butyl-3-methyl-imidazolium(BMIM) , l-methyl-3-pentyl-imidazolium(PMIM) , l-hexyl-3-methyl-imidazolium (HMIM) , l-heptyl-3-methyl-imidazolium with anion including hexafluoroantimonate (SbFβ) , hexafluorophosphate (PF₆) , tetrafluoroborate (BF₄) , trifluoromethansulfonate (OTf) , acetate (OAc) .

5. The method according to any one of claims 1 to 4, the asymmetric epoxidation was performed in the presence of the mixture of imidazolium salts of formula 1 with other organic solvent.

6. The method according to claim 5, wherein the organic solvent is selected from the group consisting of methylene chloride, chlorobenzene and benzene.

7. The method according to claim 1, wherein the chiral salen metallic catalyst has formula 2; (formula 2)

wherein R¹, R², R³ and R⁴ are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group, or R¹, R², R³ and R⁴ can be bonded each other to form Cι-C₈ rings; X¹, X², X³, X⁴, X⁵, X⁶, X⁷ and X⁸ are independently hydrogen, halogen, alkyl, silyl, silyloxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, imino, amido, phosphoryl, carbonyl or sulfonyl group. Y¹ and Y² are independently hydrogen or alkyl group. M represents transition metal; and A represents anion.

8. The method according to claim 7, wherein M is selected from the group consisting of the group consisting of Mn, Cr, Fe, Co, Ti, V, RuandOs; andA is selected fromthe group consisting of Cl, CH₃COO, PF₆, BF₄ and SbF₆.

9. The method according to claim 7 , wherein the chiral salen metallic catalyst has formula 2a; ( formula 2a)

wherein, hydrogen atoms 1 and 2 together are in trans positions; R represents alkyl group having 1 to 4 carbon atoms, halogen group, alkoxy or trialkylsilyloxy group -0-SiR¹R²R³, wherein R^R² and R³ are independently alkyl group having 1 to 4 carbon atoms; and A is selected frotm the group consisting og Cl, CH₃COO, PF₆, BF₄ and SbF₆.

10. The method according to claim 9, wherein the chiral salen metallic catalyst of the above formula 2 has formula 2b or 2c (formula 2b)

[formula 2c]

11. The method according to claim 7, wherein the chiral salen metallic catalyst has formula 2d. (formula 2d)

wherein, hydrogen atoms 1 and 2 together are in trans positions; R represents primary, secondary or tertiary alkyl group having 1 to 4 carbon atoms, halogen group, alkoxy or trialkylsilyloxy group -O-SiR^R³, wherein R^R² and R³ of alkyl group having 1 to 4 carbon atoms; and A selected from the group consisting of Cl, CH₃COO, PFβ, BF and SbF₆.

12. The method according to claim 11, wherein the chiral salen metallic catalyst of the above formula 2d has formula 2e or 2f (formula 2e)

(formula 2f)

13. The method according to claim 1 , wherein the chiral salen metallic catalyst has formula 3. (formula 3)

wherein R¹, R², R³ and R⁴ are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group, or R¹, R², R³ and R⁴ can be bonded each other to form C-Cs rings; X¹, X², X³, X⁴, X⁵ and X⁶ are independently hydrogen, halogen, alkyl, sillyl, sillyl alkoxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, imino, amido, phosphoryl, carbonyl or sulfonyl group; or X¹ and X², X⁴ and X⁵ can be bonded each other to form benzene ring; R⁵, R⁶, R⁷ and R⁸ are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group; or R⁶ and X¹, R⁸ and X⁴ can be bonded each other to form C₅-C₆ ring; Y¹ and Y² are independently hydrogen or alkyl group; M represents transition metal; and A represents anion.

14. The method according to claim 13, wherein the M is selected from the group consisting of Mn, Cr, Fe, Co, Ti, V, Ru and Os; the A is selected from the group consisting of Cl, CH₃COO, PF_S, BF₄ and SbF₆.

15. The method according to claim 14 , wherein the chiral salen metallic catalyst has formula 3a. (formula 3a)

wherein, hydrogen atoms 1 and 2 together are in trans positions; R¹ represents hydrogen or methyl group; R² represents methyl or phenyl group; and A is anion.

16. The method according to claim 13, wherein the chiral salen metallic catalyst is represented the following formula 3b. (formula 3b)

wherein, hydrogen atoms 1 and 2 together are in trans positions; R¹ represents hydrogen or methyl group; R² represents methyl, ethyl or propyl group; R³ represents hydrogen, methyl or ethyl group; R² and R³ represent mthylene group and can be bonded each other to form C₅ ring; and A is anion selected from the group consisting of Cl, CH₃COO, PF₆, BF₄ and SbF₆.

17. The method according to claim 1, wherein chiral salen metallic catalyst has formula 4 (formula 4)

wherein R¹ and R² are independently hydrogen, alkyl, carboxyl, substituted or non-substituted aryl group, wherein the substitutent of aryl group is selected from the group consisting of halogen, alkyl, alkoxy, cyano or nitro group; B represents alkyl, aryl, alkylcarbonyl, arylcarbonyl, alkylsulfonyl and arylsulfonyl; n is 1 to 3; X¹, X², X³, X⁴, X⁵, X⁶, X⁷andX⁸ are independentlyhydrogen, halogen, alkyl, silyl, silyloxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, imino, amido, phosphoryl, carbonyl or sulfonyl group; Y¹ and Y² are independently hydrogen and alkyl group; M represents transition metal; and A represents anion.

18. The method according to claim 17 , wherein the M is selected from the group consisting of Mn, Cr, Fe, Co, Ti, V, Ru and Os, the A is selected from the group consisting of group consisting of Cl, CH₃COO, PF₆, BF₄ and SbF₆.

19. The method according to claim 17 , wherein the chiral salen metallic catalyst has formula 4a.

( formula 4a)

wherein, hydrogen atoms 1 and 2 together are in trans

positions; R¹ represents primary, secondary or tertiary alkyl

group, cycloalkyl group, aryl group or heteroaryl group; R²

represents primary, secondary or tertiary group having 1 to 4

carbon atoms, halogen group, alkoxy having 1 to 4 carbon atoms;

or trialkylsilyloxy group -0-SiR¹R²R³, wherein R¹^² and R³ are

independently alkyl group having 1 to 4 carbon atoms; X presents

methylene group (-CH₂-) , carbonyl group (-CO-) or carboxyl group

(-C00-) ; and A is selected from the group consisting of Cl, CH₃COO,

PF₆, BF₄ and SbF₆.

20. The method according to claim 19, wherein the chiral salen metallic catalyst has formula 4b or 4c (formula 4b)

(formula 4c)

wherein, R is alkyl, cycloalkyl, aryl or heteroaryl group; X represents methylene group (-CH₂-) , carbonyl group (-CO-) or carboxyl group (-COO-) .

21. The method according to claim 17, wherein the chiral salen metallic catalyst has formula 4d. (formula 4d)

wherein, hydrogen atoms 1 and 2 together are in trans positions; R represents alkyl group, halogen group, alkoxy group having 1 to 4 carbon atoms; or trialkylsilyloxy group -0-SiR¹R²R³, wherein R^R² and R³ are independently alkyl group having 1 to 4 carbon atoms; and A is selected from the group consisting og Cl, CH₃COO, PF₆, BF and SbF₆.

22. The method according to claim 21, wherein the chiral salen metallic catalyst has formula 4e or 4f. (formula 4e)

(formula 4f)

23. The method according to claim 1, wherein the chiral salen metallic catalyst has formula 5. (formula 5)

wherein, X¹, X², X³, X⁴, X⁵, X⁵, X⁷ and X⁸ are independently hydrogen, halogen, alkyl, silyl, silyloxy, alkenyl, alkynyl, hydroxy, amino, nitro, thiol, imino, amido, phosphoryl, carbonyl or sulfonyl group; Y¹ and Y² are independently hydrogen and alkyl group; Z¹, Z², Z³ and Z⁴ are independently hydrogen, alkyl, halogen, cyano or nitro group; ; M represents transition metal; and A represents anion.

24. The method according to claim 23, wherein M is selected from the group consisting of Mn, Cr, Fe, Co, Ti, V, Ru and Os; and A is selected from the group consisting of Cl, CH₃COO, PFe, BF₄ and SbF₆.

25. The method according to claim 23, wherein the chiral salen metallic catalyst has formula 5a. (formula 5a)

wherein, R represents primary, secondary or tertiary alkyl group having 1 to 4 carbon atoms, halogen group, alkoxy or trialkylsilyloxy group -O-SiR^R³, wherein R^R² and R³ are independently alkyl group having 1 to 4 carbon atoms; and A is Cl, CH₃COO, PF₆, BF₄ or SbF₆.

26. The method according to claim 1, wherein the oxidizing agent is selected from the group of consisting of NaOCl, m-chloroperbenzoic acid, iodosylbenzene (PhlO) , sodium periodate and tetrabythylammonium periodate (BuNI0₄) .

27. The method according to claim 26, wherein the oxidizing agent is NaOCl.

28. A method for recovering chiral salen metallic catalyst comprising the steps of: a) performing asymmetric epoxidation of olefin in the presence of chiral salen metallic catalyst and one or more ionic liquids of formula 1 or the mixture thereof with other organic solvent; b) separating the organic layer from the reaction mixture and distillingvolatile solvent to obtain a concentratedresidue; c) adding organic solvent which is notimmiscible with ionic liquid to the residue to form two separated layers, wherein the one is an organic layer and the other is an ionic liquid layer; and, d) separating the ionic liquid layer from the two separated layers to obtain the ionic liquid solution comprising the chiral catalyst.

29. The method according to claim 28 , wherein the chiral salen catalyst was recovered as immobilized in the ionic liquid.