Cope Elimination

This transformation involves the stereoselective syn elimination of tertiary amine oxides. These amine oxide substrates are easily prepared by the oxidation of the tertiary amine with a peroxide. Common peroxides include hydrogen peroxide and peroxycarboxylic acids such as mCPBA.

To a round bottom flask equipped with a magnetic stir bar was added the amine (0.32 mmol, 1.0 eq) and DCM (3.10 mL). The solution was cooled in a dry ice/acetone bath and stirred at this temperature for 10 minutes before the addition of mCPBA (1.0 eq) as a solution in DCM, which was added dropwise to keep the solution temperature consistent. Upon completion of addition, basic alumina, Al2O3, (0.66 g/mmol of substrate) was added to the solution and was stirred 20 seconds at this temperature before the solution quickly passed through a plug of basic alumina. Concentration and purification of the filtrate via silica gel flash column chromatography afforded the desired alkene.