Asymmetric epoxidation catalyzed by novel azacrown ether-type chiral quaternary ammonium salts under phase-transfer catalytic conditions

7 ASYMMETRIC EPOXIDATION CATALYZED BY NOVEL AZACROWN ETHER-TYPE CHIRAL QUATERNARY AMMONIUM SALTS UNDER PHASE-TRANSFER CATALYTIC CONDITIONS 

Kazushige Hori, Keita Tani and Yasuo Tohda 

Division of Natural Science, Osaka Kyoiku University, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582, Japan 

5)-Oxybis[2-(ethyleneoxy)-2 -hydroxy-1,1 -binaphthyl] (2.32 g, 3.61 mmol) and potassium carbonate (l.lOg, 7.96mmol) were placed in a 300mL round-bottomed flask equipped with a reflux condenser and a magnetic stirrer bar. Dry methyl ethyl ketone (142 mL) was then added and the mixture was refluxed on an oil bath for 1 h. To this solution, Af,Af-bis-(2-p-nitrobenzenesulfonyloxyethyl)-A -p-nitrobenzenesulfonamide dichloromethane complex (3.44g, 4.32 mmol) was added. 

After the resulting mixture was heated under reflux for 24 h, the solvent was evaporated under reduced pressure. To the residue was added water (50 mL) and the mixture was extracted with dichloromethane (3 x 25 mL) using a separatory funnel. The combined organic extracts were washed with brine (25 mL), dried over anhydrous magnesium sulfate, and concentrated in vacuo to afford the crude product. 

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Hori, K., Tamura, M., Tani, K., Nishiwaki, N., Ariga, M. and Tohda, Y. Asymmetric Epoxidation Catalyzed by Novel Azacrown Ether-type Chiral Quaternary Ammonium Salts under Phase-transfer Catalytic Conditions. Tetrahedron Lett. 2006, 47, 3115-3118. 

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