1622486-76-3Relevant academic research and scientific papers
Primary amine attached to an N-(carboxyalkyl)imidazolium cation: A recyclable organocatalyst for the asymmetric Michael reaction
Kucherenko, Alexandr S.,Lisnyak, Vladislav G.,Chizhov, Alexandr O.,Zlotin, Sergei G.
, p. 3808 - 3813 (2014)
A (1S,2S)-1,2-diphenylethane-1,2-diamine derivative modified with an N-(4-carboxybutyl)imidazolium cation and PF6- anion has been developed and applied as a recyclable organocatalyst of the asymmetric 1,4-conjugate addition of 4-hydroxy-2H-chromen-2-one to 1-substituted buten-3-ones or cyclohexen-3-one to afford corresponding Michael adducts in high yields (up to 97-%) and enantioselectivities (up to 90-% ee). The most active (S) enantiomer of the clinically useful anticoagulant warfarin was prepared in this way. The catalyst exhibited better recyclability than its known analog, which does not contain a carboxy group: it could be recycled 5 times in the reaction without a significant decrease in product yield or ee values. Gradual deactivation of the catalyst was caused by leaching during workup rather than by off-cycle reactions between the catalyst and reagents. The sustainability of ionic-liquid-supported primary-amine-derived recyclable chiral organocatalyst of practical important in asymmetric Michael reactions has been improved by incorporating a peripheral carboxylic group that suppresses undesirable off-cycle reactions during the catalytic process. Copyright
