Easy separation and reutilization of the Jacobsenʹs catalyst in olefin oxidation Original Research Article

A new method for recycling the Jacobsenʹs catalyst used for the catalytic oxidation of R-(+)-limonene and cis-ethyl cinnamate at room temperature by in situ generated dimethyldioxirane (DMD) as oxidizing agent is presented. Neither the immobilization of the catalyst to the solid support nor modification of its chemical structure is involved in this method. Therefore, the excellent catalytic properties of the Jacobsenʹs catalyst could be retained. Limonene diepoxide was the main product of the oxidation of R-(+)-limonene, whereas a single epoxide with good enanantioselectivity (78% ee) was obtained in the asymmetric oxidation of cis-ethyl cinnamate. On the other hand, R-(+)-limonene showed to be more reactive than cis-ethyl cinnamate. In both cases, the catalyst was recovered and recycled without appreciable loss of its initial catalytic activity.