Chiroptical Properties of 1,2-Cyclopropanedicarboxylic Anhydrides and Imides. The Cyclopropane Ring Contribution to the Cotton Effect

Article abstract of DOI:10.1021/jo00064a034

Several optically active 1,2-cyclopropanedicarboxylic anhydrides and imides were prepared and their chiroptical spectra studied.Despite the strained bicyclicc skeleton of these compounds, their CD spectra show an unusual solvent dependence.This phenomenon can be explained in terms of the cyclopropane ring contribution to the Cotton effect.A deviation of the skeleton and the anhydride or imide group from the local C_s symmetry, shown by MNDO calculations, causes formation of an inherently chiral chromophore constituted by the three-membered ring and neighboring carbonyls.This kind of chromophore is responsible for the observed strong Cotton effects.