The rotameric (R*,S*)- and (R*,R*)-biaryl-3,3′-diphthalides of polyphenylene series

A wide range of diastereomeric pairs of biaryl-3,3′-diphthalides with aromatic (heteroaromatic) substituents of polyphenylene series (including halogen substituted) was synthesized. All of them were separated and characterized by the methods of X-ray analysis, HPLC, IR-, 1H and 13C NMR spectroscopy. It was determined that solubility, tendency to adsorption and related to it retention times, chemical shifts of equivalent hydrogen and carbon atoms of biaryl-3,3′-diphthalides diastereoisomers are determined firstly by the stereo-electronic effects of two adjacent strongly polar phthalide groups. It was shown that both in crystalline phase and in solution all the diphthalides, regardless of the chemical structure of their substituents, are existing as stable rotamers with cis or synperiplanar (chiral forms) and trans or antiperiplanar (meso-forms) conformation.