Effect of the substrate and catalyst chirality on the diastereoselective epoxidation of limonene using Jacobsen-type catalysts.
Chiral and achiral Jacobsen's catalysts in their homogeneous form or immobilized on Al-MCM-41 exhibit similar catalytic activity during diastereoselective epoxidation of limonene when in situ generated dimethyldioxirane is used as oxidizing agent. Experimental observations suggest that not only the catalyst chiral center but also the substrate chiral center participates in the preferential formation of most diastereomers. Remarkable turnover numbers (TON), up to 288, was achieved over the heterogeneous catalysts in comparison to their homogeneous counterparts (TON up to 46). Catalyst leaching rather than catalyst oxidative degradation was identified as the main source of catalyst deactivation during reutilization tests.
Cubillos
Jairo
J
Chemical Engineering Department, Universidad de Antioquia, Medellín, Colombia. jacubil@gmail.com
Vargas
María
M
Reyes
Juliana
J
Villa
Aída
A
Montes De Correa
Consuelo
C