Atropisomerism of Methyl Maleopimaric N-Arylimides and Their Kinetics Analysis

During the last few years, considerable interest has been focused on the atropisomerism of N-aryl bond contain compounds which belong to one of the most common classes with atropisomers. Six N-aryl methyl maleopimaric acid diimides(4a-4f) were synthesized from aromatic amines andmaleopimaric acid trimethyl ester(3). The structures of the compounds were characterized by H-1 NMR,C-13 NMR and MS. The atropisomerism and kinetics analyses of the N-(1-naphthyi) maleopimaric acid diimides were carried out by 1H NMR. In the course of preparing resin-based chiralregent, atropisomerism was found in N-(1-naphthy) maleopimaric acid diimides(4f). The N-(1-phenyl) maleopimaric acid diimide (4a), N-(2-carboxy phenyl) methyl maleopimaric acid diimide (4b), N-(2-nitrophenyl)-methyl maleopimaric acid diimide (4c), N-(2-chlorophenyl) -methyl maleopimaric acid diimide(4d) and N-[1-(2-amine)-phenyl]-methyl maleopimaric acid diimide (4e) did not exist atropisomerism due to the smaller. steric effects. The results indicated that maleopimaric N-naphthylimide (4f) underwent slow trans-cis conversion and induced in a gradual change of different [trans]/[cis] ratio during dissolution in CDCl3 at ambient temperature.