Organocatalysts ionic-liquid-tagged

Chiral 1,2,3-triazolium ionic liquid tethered pyrrolidine catalysts built from (S)-proline and its derivatives have been successfully ap>plied in various catalytic reactions (Khan, Shah et al. 2010 Khan, Shah et al. 2010 Maltsev, Kucherenko et al. 2010 Yacob, Shah et al. 2008). The 1,2,3-triazolium ionic liquid-tagged organocatalysts derived from proline and its derivatives are mostly viscous liquids at room temperature and are completely miscible with polar solvents such as methanol, chloroform, acetonitrile, dimethylsulfoxide, dimethylformamide and water. They are insoluble in less-polar solvents such as n-hexane and diethyl ether. In some cases, the ionic liquid sub-unit serves not only as a phase tag for efficient recycling but also as an effective chiral amplifier through polar interactions and steric shielding. 

Catalytic application of the triazolium ionic liquid tagged organocatalysts 25 and 26 gave very interesting results in the Michael addition of various unmodified aldehydes and ketones to trfl s- -nitrostyrenes. 10 mol % phenyl substituted ionic liquid tagged organocatalyst 25 provided excellent yields (>99%), diastereoselectivities (>99 1) and... 

Scheme 5. Synthesis of (S)-proline derived 1,2,3-triazolium ionic liquid tagged organocatalysts 25 and 26...

Khan, S. S. J. Shah and J. Liebscher (2011). "Ionic-liquid tagged prolines as recyclable organocatalysts for enantioselectiive a-aminoxylations of carbonyl compounds." Tetrahedron Vol.67, 0an 15, 2011), pp. 1812-1820 ISSN 0040-4020... 

Yacob, Z. (2010). 1,2,3-Triazolium Ionic Liquid Tagged Catalysts in Asymmetric Organocatalysts Department of Chemistry and Bioorganic Chemistry. Berhn, Humboldt University of Berlin. 

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