479423-20-6Relevant articles and documents
Stereoselective nucleophilic addition to imines catalyzed by chiral bifunctional thiourea organocatalysts
Puglisi, Alessandra,Benaglia, Maurizio,Annunziata, Rita,Rossi, Davide
experimental part, p. 2258 - 2264 (2009/04/04)
A new and easy synthesis of chiral bifunctional organic catalysts obtained by the combination of (S)-t-leucine-derivatives with (1R,2R)-trans-1,2-diamino-cyclohexane was developed. A few compounds, representatives of a class of organocatalysts containing a thiourea group and a tertiary amino group connected through a chiral backbone, have been successfully synthesized. The catalytic behaviour of such bifunctional chiral molecules, either neutral or protonated species, was investigated in the addition of acetylacetone to β-nitrostyrene as a model reaction. Using the best conditions, high yields and enantioselectivities of up to 85% were obtained. The same metal free catalysts were then employed in the addition of activated nucleophiles to imines: in the reaction of 1,3-diketones with N-CBz imines, the products were isolated in up to 61% ee, while in the reaction with diethyl malonate enantioselectivities up to 71% were reached.
Asymmetric catalytic Mannich reactions catalyzed by urea derivatives: Enantioselective synthesis of β-aryl-β-amino acids
Wenzel, Anna G.,Jacobsen, Eric N.
, p. 12964 - 12965 (2007/10/03)
Highly enantioselective addition reactions between silyl ketene acetals and N-Boc aldimines are catalyzed by the thiourea-based catalyst 1c. Extraordinary scope is observed in this methodology with regard to the imine substrate, with aryl and heteroaromatic derivatives generally affording nearly quantitative yields of β-amino ester product in up to 98% enantioselectivity. Copyright
