Novel thiourea-amine bifunctional catalysts for asymmetric conjugate addition of ketones/aldehydes to nitroalkenes: rational structural combination for high catalytic efficiency
A series of thiourea-amine bifunctionalcatalysts have been developed by a rational combination of prolines with cinchona alkaloids, which are connected by a thiourea motif. The catalyst 3a, prepared from L-proline and cinchonidine, was found to be a highly efficient catalyst for the conjugateaddition of ketones/aldehydes to a wide range of nitroalkenes (up to 98/2 dr and 96% ee). The privileged cinchonidine
Synthesis of a New N-Diaminophosphoryl-N′-[(2S)-2-pyrrolidinylmethyl]thiourea as a Chiral Organocatalyst for the Stereoselective Michael Addition of Cyclohexanone to Nitrostyrenes and Chalcones - Application in Cascade Processes for the Synthesis of Polyc
作者:Carlos Cruz-Hernández、Eduardo Martínez-Martínez、Perla E. Hernández-González、Eusebio Juaristi
DOI:10.1002/ejoc.201801339
日期:2018.12.31
novel chiralthiourea containing a segment of privileged (2S)‐2‐pyrrolidinylmetan‐amine as well as a hydrophobic phosphoramide framework is described. The new organocatalyst exhibited good performance in asymmetricMichaeladditions, in a variety of systems including the formal [3+3] cyclization of cyclohexanone with arylidenepyruvates through a cascade process, which involves the asymmetric Michael
Chiral Imidazolium Ionic Liquids Derived from (<i>S</i>
)-Prolinamine as Organocatalysts in the Asymmetric Michael Reaction and Michael-Aldol Cascade Reaction under Solvent-Free Conditions
The synthesis of three new chiral imidazolium ionic liquids (prepared by the combination of one new chiral organic cation with different anions) and their application in the enantioselective Michaelreaction between cyclohexanone and substituted nitrostyrenes under solvent-free conditions is described. In addition, the first asymmetriccascade Michael-aldol reaction of cyclohexanone and benzylidenepyruvate
Highly Enantioselective Michael Additions in Water Catalyzed by a PS-Supported Pyrrolidine
作者:Esther Alza、Xacobe C. Cambeiro、Ciril Jimeno、Miquel A. Pericàs
DOI:10.1021/ol071366k
日期:2007.9.1
organocatalyst for the Michaeladdition of ketones to nitroolefins is described. A 1,2,3-triazole ring, constructed through a click 1,3-cycloaddition, plays the double role of grafting the chiral pyrrolidine monomer onto the polystyrene backbone and of providing a structural element, complementary to pyrrolidine, key to high catalytic activity and enantioselectivity. Optimal operation in water and full recyclability
Asymmetric Michaeladditionreactions of unmodified ketones to nitroalkenes were performed in PEGs catalyzed by novel pyrrolidinyl-thioimidazolium salts to give products in up to 97% yield and 99% enantioselectivity; ESI mass spectrometric detection for the first time gave evidence of the presence of the PEG-organocatalyst host-guest complex.