Highly enantio- and diastereoselective Michael addition of cyclohexanone to nitroolefins catalyzed by a chiral glucose-based bifunctional secondary amine-thiourea catalyst
A novel bifunctional thiourea bearing a saccharide-scaffold and a secondary amino group was synthesized, and was proven to be an effective organocatalyst for the asymmetric Michael reaction of cyclohexanone to both aryl and alkyl nitroolefins. The corresponding adducts were obtained with excellent diastereo- (up to >99/1 dr) and enantioselectivities (up to 97% ee).
Polymer-Supported Enantioselective Bifunctional Catalysts for Nitro-Michael Addition of Ketones and Aldehydes
作者:Lital Tuchman-Shukron、Scott J. Miller、Moshe Portnoy
DOI:10.1002/chem.201102474
日期:2012.2.20
L‐amino acid as a spacer and a urea‐forming moiety in a polymer‐supported bifunctional urea–primary amine catalyst, based on (1R, 2R)‐(+)‐1,2‐diphenylethylenediamine, significantly improves the catalyst’s activity and stereoselectivity in the asymmetric addition of ketones and aldehydes to nitroolefins. Yields and enantioselectivities, unprecedented for immobilized catalysts, were obtained with such challenging
4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether as a highly efficient bifunctional organocatalyst for Michael addition of ketones and aldehydes to nitroolefins
作者:Chao Wang、Chun Yu、Changlu Liu、Yungui Peng
DOI:10.1016/j.tetlet.2009.02.211
日期:2009.5
4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether bifunctionalorganocatalyst 3a is a highly efficient catalyst for the asymmetric Michaeladdition reactions of ketones and aldehydes to nitrostyrenes, leading to syn-selective adducts with excellent yields (>99%), high diastereoselectivities (up to 99:1 dr) and excellent enantioselectivities (up to 99% ee). Control experiments suggested that the
Asymmetric Michael Addition Induced by the Anion of an Imidazolium Salt
作者:Vincent Gauchot、Julien Gravel、Andreea R. Schmitzer
DOI:10.1002/ejoc.201201068
日期:2012.11
We describe the application of a chiral catalytic imidazoliumsalt derived from trans-L-hydroxyproline, the anion being the catalytic entity, as a catalyst for the asymmetricMichaeladdition. We report the first example of a catalytic Michaeladdition using this type of catalyst, leading to excellent yields (up to 99 %) and good selectivities (up to 99:1 dr, up to 82 % ee).
A modular sugar-based pyrrolidine (3) was prepared and was found to be a highly enantioselective organocatalyst for the asymmetric Michael addition of ketones to nitrostyrenes. In the presence of 10 mol% of 3, a pyrrolidine unit anchored to a natural D-glucose backbone through click chemistry, the Michael additions of ketones to nitrostyrenes proceeded smoothly to generate the corresponding adducts