Kinetic Separation of cis- and trans-Limonene Epoxide: Reaction of Diastereomeric Mixture of Limonene Oxides with Secondary Amine and Carbamate

M.M. El Hammoumi1,2,*, L. Ait Said1, A. El Bachiri1 and M. Khoukhi1

1Bio-Geosciences and Material Engineering Laboratory “LBGIM” Ecole Normale Superieure, Hassan II University, Casablanca, Morocco

2Applied Organic Chemistry Laboratory, Faculty of Science and Technology, University Sidi Mohamed Ben Abdellah, Fes, Morocco

*Corresponding author: E-mail: moji82003@yahoo.fr

Abstract

A simple kinetic separation of (1:1) diastereomeric mixture of limonene oxides was used to purify cis- and trans-diastereomers of (R)-(+)-limonene oxide. The epoxide ring of trans-isomer was selectively opened by (R)-N-methyl-(α-methyl-benzyl)amine. This secondary nucleophilic amine left cis-limonene oxide largely unreacted and was obtained up to 90% yield. In a diverse way, (R)-N-(α-methyl-benzyl) ethyl carbamate, selectively catalyze hydrolysis of cis-limonene oxide to 1,2-limonene diol leaving trans-limonene oxide largely unreacted. The unreacted trans-limonene oxide was recovered in up to 75% yield. HPLC and NMR analyses were used to demonstrate that the isolation of cis- and trans-diastereomers of (R)-(+)-limonene oxide has shown that > 98% were pure. As a result, depending on the realization of the secondary amine or carbamate in the presence of water, either cis- or trans-limonene oxide may be obtained in high diastereomeric purity.

Keywords

Kinetic separation, Limonene oxide, Diastereomer resolution, Secondary amine, Carbamate.

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