1174340-53-4Relevant academic research and scientific papers
Polymer-supported enantioselective bifunctional catalysts for nitro-Michael addition of ketones and aldehydes
Tuchman-Shukron, Lital,Miller, Scott J.,Portnoy, Moshe
supporting information; experimental part, p. 2290 - 2296 (2012/03/27)
Introduction of an 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 donors as acetone, cyclopentanone, and α,α-disubstituted aldehydes, which usually perform inadequately in this reaction (particularly when a secondary-amine-based catalyst is used). Remarkably, though in the examined catalysts the D-amino acids as spacers were significantly inferior to the L isomers, for the chosen configuration of the diamine (match-mismatch pairs) the size of the side chain of the amino acid hardly influenced the enantioselectivity of the catalyst. These results, combined with the reactivity profile of the catalysts with substrates bearing two electron-withdrawing groups and the behavior of the catalysts' analogues based on tertiary (rather than primary) amine, suggest an enamine-involving addition mechanism and a particular ordered C-C bond-forming transition state as being responsible for the catalytic reactions with high enantioselectivity. Copyright
Highly enantioselective michael addition of acetone to nitro olefins catalyzed by chiral bifunctional primary amine-thiophosphoramide catalyst
Lu, Aidang,Liu, Tao,Wu, Ronghua,Wang, Youming,Zhou, Zhenghong,Wu, Guiping,Fang, Jianxin,Tang, Chuchi
experimental part, p. 5777 - 5781 (2011/01/04)
A series of bifunctional primary amine-thiophosphoramides were synthesized, which proven to be effective organocatalysts for the asymmetric Michael reaction of acetone to both aryl and alkyl nitro olefins in the presence of phenol as a protic additive. The corresponding adducts were obtained in excellent chemical yields (up to >99%) with excellent enantioselectivities (up to 97% ee). A novel chiral phosphoramide functions well as an efficient bifunctional organocatalyst for the asymmetric Michael addition of acetone, one of the most challenge substrate in Michael addition, to nitro olefinsto afford the corresponding syntheticvaluable γ-nitro ketones in good to excellent yield with high levels of enantioselectivities (up to 97% ee, respectively).
