Highly enantioselective Michael addition of 1,3-dicarbonyl compounds to nitroalkenes catalyzed by designer chiral BINOL–quinine–squaramide: efficient access to optically active nitro-alkanes and their isoxazole derivatives
摘要:
A chiral BINOL-quinine-squaramide has been identified as the best catalyst for the asymmetric Michael addition of nitroalkenes to 1,3-dicarbonyl compounds. A series of chiral nitroalkanes were prepared with approximately >99% ee. Furthermore, the methodology was applied successfully to the synthesis of enantiomerically pure isoxazoles derivatives (>99% ee). (C) 2013 Elsevier Ltd. All rights reserved.
Asymmetric Michael addition reactions catalyzed by a novel upper-rim functionalized calix[4]squaramide organocatalyst
作者:Ke Yang、Zhiyan Ma、Hong-Xiao Tong、Xiao-Qiang Sun、Xiao-Yu Hu、Zheng-Yi Li
DOI:10.1016/j.cclet.2020.02.057
日期:2020.12
Abstract A novel upper-rim functionalizedcalix[4]squaramide organocatalyst bearing bis-squaramide and cyclohexanediamine scaffolds was designed and prepared to catalyse a serial of asymmetric Michael addition of 1,3-dicarbonyl compounds to α,β-unsaturated carbonyl compounds in high yields (up to 99 %) and good to excellent enantiomeric excesses (up to 99% ee). The comparative experiments indicated
A low loading of a quinine-derived squaramide efficiently catalyzes the triple-domino Michael/aza-Henry/cyclization reaction between 1,3-dicarbonyl compounds, β-nitroolefins, and aldimines to provide tetrahydropyridines bearing three contiguous stereogenic centers in good yields, excellent enantiomeric excesses, and up to high diastereomeric ratios.
A series of new modular bifunctional chiral thiourea organocatalysts were synthesized from natural Cinchona alkaloids and amino acids, and their performance in the aza-Henry reaction of nitroalkanes to imines, the Michaeladdition of acetylacetone to nitroolefins and the Michaeladdition of acetone to nitroolefins was investigated. Under the mild conditions, the important building blocks β-nitro amines
A novel and recyclable catalyst, a C3-symmetrical cinchonine-squaramide, has been developed for the asymmetric Michaeladdition of 1,3-dicarbonylcompounds to nitroalkenes. When using only 1 mol% of catalyst 1a for the reaction, high reaction yields with excellent enantioselectivities and diastereoselectivities (up to 96% yield,>99% ee,>99:1 dr) were achieved, in which the results for cyclic keto esters
Ephedrine- and Pseudoephedrine-Derived Thioureas in Asymmetric Michael Additions of Keto Esters and Diketones to Nitroalkenes
作者:Carsten Bolm、Angelika Flock、Anke Krebs
DOI:10.1055/s-0029-1219582
日期:2010.5
Ephedrine-derived bifunctional thioureas have been synthesized and applied as organocatalysts in Michael additions of 1,3-dicarbonyl compounds to nitroalkenes.