Title of article :
Osmium catalyzed asymmetric dihydroxylation of methyl trans-cinnamate in ionic liquids, followed by supercritical CO2 product recovery
Author/Authors :
Ana Serbanovic، نويسنده , , Luis C. Branco، نويسنده , , Manuel Nunes da Ponte، نويسنده , , Carlos A.M Afonso، نويسنده ,
Issue Information :
دوفصلنامه با شماره پیاپی سال 2005
Abstract :
In this work, osmium-catalyzed asymmetric dihydroxylation (AD) of methyl trans-cinnamate was studied. Osmium and chiral ligand catalysts were immobilized in ionic liquid only, without any other reaction solvents, while the recovery of the product was performed by extraction with supercritical CO2, and compared with results obtained by extractions with organic solvents such as hexane and diethyl ether. In supercritical CO2 extraction experiments, optimal extraction pressure was found and ionic liquid chosen, so that the highest reaction yields coupled with lowest osmium content in the crude product can be achieved. Finally, recycle experiments of the same (ionic liquid + catalytic system) mixture were successfully conducted. Application of ionic liquids and supercritical CO2 in osmium catalyzed AD allows for the isolation of the diol basically without contamination with osmium, in high yield and enantiomeric excess, and it makes possible the efficient reuse of ionic liquid solvent and the catalytic system.
Keywords :
Asymmetric dihydroxylation , Ionic liquids , Supercritical CO2 , Catalyst reuse , Taxol side chain , Osmium contamination
Journal title :
Journal of Organometallic Chemistry
Journal title :
Journal of Organometallic Chemistry