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 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
Supported and Unsupported Chiral Squaramides as Organocatalysts for Stereoselective Michael Additions: Synthesis of Enantiopure Chromenes and Spirochromanes
作者:José M. Andrés、Jorge Losada、Alicia Maestro、Patricia Rodríguez-Ferrer、Rafael Pedrosa
DOI:10.1021/acs.joc.7b01177
日期:2017.8.18
Novel supported chiral bifunctional squaramides have been easily prepared starting from diamines derivedfrom natural amino acids and commercially available aminoalkyl polystyrene resins. These squaramides behave as excellent stereoselective recoverable organocatalysts in different Michael additions, in neat conditions at room temperature. The reaction on 2-(2-nitrovinyl) phenol as electrophile lead
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.
Doubly stereocontrolled asymmetric conjugate addition of acetylacetone to nitroolefins catalyzed by bifunctional tertiary amine–thiourea catalysts derived from both acyclic α-amino acids and carbohydrates
preparative, cheap, and fine-tunable bifunctional chiral tertiary amine–thiourea organocatalysts have been developed by combining both acyclic diamines derived from acyclic α-amino acids and carbohydrates. These organocatalysts promoted the enantioselective conjugate addition of acetylacetone to various nitroolefins in good yields (up to 93%) with good enantioselectivities (up to 91% ee). The present research