Easy separation and reutilization of the Jacobsen's catalyst in olefin oxidation

A new method for recycling the Jacobsen's 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 Jacobsen's 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.

Graphical abstractA new method for recycling the Jacobsen's catalyst applied to the catalytic oxidation of R-(+)-limonene and cis-ethyl cinnamate at room temperature using in situ generated dimethyldioxirane (DMD) as oxidizing agent is presented. The strategy was to vary the solubility of the catalyst during reaction. The catalyst was quite stable towards oxidative degradation.Figure optionsDownload full-size imageDownload as PowerPoint slide