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Magnetic-Nanoparticle-Supported Chiral DMAP as a Recyclable Organocatalyst
O. Gleeson, R. Tekoriute, Y. K. Gunko, S. J. Connon*
The University of Dublin, Ireland
22 June 2009 (online)
The authors report the synthesis and application of magnetic nanoparticles covalently linked to a chiral DMAP analogue. The resulting heterogeneous organocatalyst 1 was applied to a kinetic resolution of monoprotected cis-diol 2 (see Scheme). The resolved alcohol was obtained with 99.5:0.5 er and 72% conversion after the first run. The authors recovered the catalyst by applying an external magnet and decanting the reaction mixture. Reusing the catalyst in a total of 20 iterative cycles caused only a minor decrease in the catalyst efficiency which could be remedied by a slight excess of reagents. The catalyst also proved to be robust with other alcohol substrates. No microscopic degradation of the nanoparticles was detected even after the 32nd cycle.