Abstract
The hemilabile chiral C-2 symmetrical bidentate substituted amide ligands (1R, 2R)-5(a-d) and (1S, 2S)-6(a-d) were synthesized in quantitative yield from (1R, 2R)-(+)-3-methylenecyclo-propane-1,2-dicarboxylic acid (1R, 2R)-3 and (1S, 2S)-(-)-3-methylenecyclopropane-1,2-dicarboxylic acid (1S, 2S)-3, in two steps, respectively. The chiral Feist's acids (1R, 2R)-3 and (1S, 2S)-3 were obtained in good isomeric purity by resolution of trans-(+/-)-3-methylene-cyclopropane-1,2-dicarboxylic acid from an 8: 2 mixture of tert-butanol and water, using (R)-(+)-alpha-methylbenzyl amine as a chiral reagent. This process is reproducible on a large scale. All these new synthesized chiral ligands were characterized by H-1-NMR, C-13-NMR, IR, and mass spectrometry, as well as elemental analysis and their specific rotations were measured. These new classes of C-2 symmetric chiral bisamide ligands could be of special interest in asymmetric transformations.