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
chiral solid catalysts and their homogenous counterparts exhibited high activities both enantioselective transfer hydrogenation reaction (up to 99% conversion and 65% ee) and enantioselective Michael reaction (up to 98% conversion and 26% ee). Moreover, the SBA‐15 supported solid catalysts were separated from the reaction mixture by simple filtration, whereas the magnetic MCM‐41 supported solid catalysts
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.
Novelbifunctionalchiralsquaramide–amine organocatalysts have been developed by rational combination of pyrrolidine and a cinchona alkaloid. The catalysts promoted the enantioselective Michael addition of both mono- and diketones to a broad range of nitroalkenes providing the corresponding products in moderate to high yields with excellent enantioselectivities and diastereoselectivities (up to 96%