95341-81-4Relevant academic research and scientific papers
COPPER(II) IN ORGANIC SYNTHESIS. X. THE IMPORTANCE OF STERIC HINDRANCE IN THE DESIGN OF CHIRAL TRIDENTATE LIGAND COPPER(II) CATALYSTS FOR ENANTIOSELECTIVE MICHAEL REACTIONS
Desimoni, Giovanni,Faita, Giuseppe,Mellerio, Giorgio,Righetti, Pier Paolo,Zanelli, Claudio
, p. 269 - 273 (2007/10/02)
Several copper(II) complexes with tridentate chiral ligands derived from 2-substituted 2-aminoethanols have been tested as catalysts for enantioselective Michael reactions.The degree of enantioselection increases with the increase of the steric hindrance of the substituents and the best result (65percent e.e.) was obtained with the benzyl-substituted catalyst.A comparison of these results with those obtained with complexes derived from 2-amino-1-indanols gives useful information about the requirements for the optimization of the catalyst design.
Enantioselective Cyclopropanation of 1,1-Diphenylethylene and Diazoacetic Acid Ester with Copper Catalysts
Brunner, Henri,Miehling, Wolfgang
, p. 1237 - 1254 (2007/10/02)
Copper(II) compounds catalyze the reaction of 1,1-diphenylethylene with diazoacetic acid ethylester.The main product is 2,2-diphenylcyclopropane carboxylic acid ethylester.The formation of the carbene dimerization products fumaric and maleic acid diethylester can be suppressed by the continuous addition of diazoacetic ester to 1,1-diphenylethylene. 37 optically active ligands, partly new, were combined with copper(II)-acetate to give in-situ-catalysts.In five cases isolated copper complexes were used as catalysts.The best optical inductions in the formation of 2,2-diphenylcyclopropane carboxylic acid ethylester with up to 65.6percent ee were achived with Schiffbase ligands, which derive from salicylaldehyde and amino alcohols, obtained from amino acid esters and phenyl Grignard. - Keywords: Catalytic enantioselective cyclopropanation; Copper(II) catalysts; Optical induction.
