Enantioselective Cyclopropanation of 1,1-Diphenylethylene and Diazoacetic Acid Ester with Copper Catalysts

Article abstract of DOI:10.1007/BF00809355

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.