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
An efficient, organocatalyticenantioselectiveaddition of cyclic diketones with β,γ-unsaturated α-keto esters has been developed that affords products in high yields (up to 95 %) and excellent enantioselectivity (up to >99 % ee) under mild conditions with a low catalyst loading (2.5 mol-%). The unsaturated α-keto esters are effectively coordinated and activated through hydrogen bonds with the squaramides
Highly Enantioselective Michael Addition of Cyclic Diketones to β,γ-Unsaturated α-Keto Esters Catalyzed by Squaramide Organocatalyst
作者:Zhi-Wei Ma、Chuan-Chuan Wang、Quan-Jian Lv、Xiao-Pei Chen、Ai-Qin Li、Jing-Chao Tao
DOI:10.1055/s-0040-1719863
日期:2022.4
developed and applied to the asymmetric Michaeladdition of cyclic diketones to β,γ-unsaturated α-keto esters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of synthetically and pharmaceutically useful chiral bicyclic compounds were obtained in high yields (up to 97%) with excellent enantioselectivities (up to 99 % ee). Furthermore, this
A series of Cinchona alkaloid-derived dimers were obtained in high yields in copper-catalyzed 1,3-dipolar “click” cycloaddition using bis(TMS)butadiyne and other bivalent alkynes. The products with bitriazole linkers were effective ligands for asymmetric copper-catalyzed Michael addition. It was shown that the presence of such linker was responsible for effective chirality transfer.