Green Epoxidation of Chalcones

Read Preparation of epoxides and reactions of epoxides in your lecture textbook 

Dispose of all aqueous wastes in the container designated for aqueous waste. Place the organic waste in the nonhalogenated organic waste container. 

50 mmole of your selected chalcone from Experiment 61,3.5 mL of methanol, and a stir bar to a 50-mL round-bottom flask. Stir and gently heat the mixture for a few minutes to see if the chalcone will dissolve in methanol. If the chalcone does dissolve, proceed to the next paragraph. Most chalcones require some dimethylsul-foxide (DMSO) in addition to methanol to dissolve. Gradually add DMSO in 0.5-mL portions using a plastic Pasteur pipette imtil the chalcone dissolves with slight heating and stirring. It may take as much as 1 to 3 mL of DMSO to completely dissolve the chalcone. Now cool the round-bottom flask to room temperature. Some of the chalcone may precipitate as the temperature is lowered to room temperature, but the majority of the chalcone will remain in solution. You may proceed with the next step even if some solid remains. 

25 mL of 2 M aqueous sodium hydroxide using a plastic disposable pipette. Now add 65 fiL of 30% hydrogen peroxide using an automatic pipette. Support the flask in an ice-water bath with a clamp, but do not stopper the flask. Stir the mixture in an ice bath for I hr. Add more ice when necessary to keep the mixtme between 0 and 2°C. Some chalcone will precipitate when the flask is cooled in the ice bath, but this should not be of concern because the chalcone will be converted to the epoxide even if some solid remains. Do not add any more DMSO. 

Following the I-hr reaction period, discontinue the stirring and add 5 mL of ice-cold water. A solid or possibly an oil should form. To extract the epoxide from the aqueous layer, add 10 mL of diethyl ether to the flask. Swirl the flask to help the epoxide 

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Synthesis of Naproxen (Aleve ) by palladium catalysis Green Epoxidation of Chalcones Cyclopropanation of Chalcones... 

C. Morisseau, G. Du, J. W. Newman, B. D. Hammock, Mechanism of Mammalian Soluble Epoxide Hydrolase by Chalcone Oxide Derivatives , Arch. Biochem. Biophys. 1998, 356, 214 - 228 C. Morisseau, M. H. Goodrow, D. Dowdy, J. Zheng, J. F. Greene, J. R. Sanborn, B. D. Hammock, Potent Urea and Carbamate Inhibitors of Soluble Epoxide Hydrolases , Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 8849 - 8854. 

Fig. 4. Catalytic activity and selectivity of solid phase-bound L-leucine oligomers. Green columns enantiomeric excess of the product epoxide 5. Blue columns conversion of the substrate chalcone (4) after 24 h...

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