An efficient synthesis of chiral phosphinyl oxide pyrrolidines and their application to asymmetric direct aldol reactions
作者:Xue-Wei Liu、Thanh Nguyen Le、Yunpeng Lu、Yongjun Xiao、Jimei Ma、Xingwei Li
DOI:10.1039/b811581h
日期:——
Chiral pyrrolidine-based phosphinyl oxides were synthesized and their performance as organocatalysts for asymmetricdirectaldolreactions was evaluated. High enantioselectivities and diastereoselectivies were achieved for a range of cyclic ketones and aromatic aldehydes.
Asymmetric Aldol Reaction Catalyzed by Modularly Designed Organocatalysts
作者:Debarshi Sinha、Tanmay Mandal、Sanjib Gogoi、Joshua J. Goldman、John Cong-gui Zhao
DOI:10.1002/cjoc.201200639
日期:2012.9.27
are amino acids and cinchona alkaloid derivatives, leads to the direct formation of the desired organocatalysts without any synthesis. These modularlydesignedorganocatalysts (MDOs) may be used for catalyzedasymmetricaldolreaction. Depending on structure of the aldehyde substrates, the corresponding aldol products may be obtained in mediocre to excellent ee values (up to 92% ee) with moderate diastereoselectivities
(S)-NOBIN-L-prolinamide was employed as organocatalyst in the direct aldol reactions of different ketones and aromatic aldehydes using dioxane as solvent and in the presence of water as additive. Acetone led to the aldol products in up to 93% ee, while cyclic ketones furnished the anti-aldols in moderate to high yield, excellent diastereoselectivity (up to > 99/< 1 anti/syn ratio) and high ee (up to 95%). (c) 2007 Elsevier Ltd. All rights reserved.
Sterically and Electronically Tunable and Bifunctional Organocatalysts: Design and Application in Asymmetric Aldol Reaction of Cyclic Ketones with Aldehydes
tunable and bifunctional organocatalysts have been developed and evaluated in the direct aldolreaction of heterocyclic ketones. Catalysts with different substituents showed variablecatalytic efficiency for analogous substrates, indicating the importance of fine-tuning the strength of the hydrogen bonding in the two NH groups. The reactions all proceeded in good to high yield and with excellent enantioselectivities