THEORETICAL-STUDIES IN MOLECULAR RECOGNITION - ASYMMETRIC INDUCTION OF BENZOPHENONE IMINE ESTER ENOLATES BY THE BENZYLCINCHONINIUM ION

Molecular-recognition techniques are used to examine the complexes formed between a chiral phase-transfer catalyst and enolates that are known to be alkylated enantioselectively. The ion pairs have well-defined, albeit flat, intermolecular potential energy surfaces that show binding regions consistent with a proposed model. The influence of dispersion vs Coulomb forces on these potential energy surfaces is addressed as is the origin of enantiofacial selectivity. An energy-partitioning algorithm that statistically weights intermolecular interaction energies for all orientations of the two molecules in the complex is used to determine which fragments of the cinchoninium ion are most responsible for enolate binding. The roles other molecular fragments play, on both the catalyst and the enolate, for ion pairing are examined.