Effect of substrate and catalyst chirality on the diastereoselective epoxidation of R-(+)-limonene with manganese(III) salen complexes

The asymmetric epoxidation of R-(+)-limonene in the presence of the Jacobsen's catalyst in its chiral and achiral either homogeneous or heterogeneous (immobilized on Al-MCM-41) forms was studied using in situ generated dimethyldioxirane as oxidizing agent. It was found that the catalytic activity of the chiral and achiral forms of the Jacobsen's catalyst was very similar either homogeneous or heterogeneous. This result suggests that the preferential formation of cis-(+)-1,2-limonene oxide depends not only on the catalyst chiral center, but also oil the substrate chiral center. This represents a clear advantage from the economical point of view since the achiral catalyst is much less expensive than its chiral counterpart.