Abstract
A high diasteroselectivity in pyrrolidinone enolate alkylations was previously studied using enolate anion as a model. Houk et al. Proposed that torisional strain between reagent and β-hydrogen and steric effects should control diastereo selectivity. Meyers et al. proposed that the π-facial difference in FMO extension in the ground state should control diastereoselectivity. We investigated possible enolate species of the enolate system in THF using the PCM method. Recently, we have proposed that the origin of this selectivity may be the populations of the initial complexes and that the torsional strain in the transition state is not important, based on the calculation performed in gas phase and PCM method. But the dielectric continiuum methods (PCM etc.) have been criticized as less sensitivity near the solute. Therefore we employed the cluster model using dimethylether (as the calculation model) for both the ground state and the transition state of pyrrolidinone enolate. The number of solvent coordination is one, and it was strongly suggested that selectivity may be controlled by the population of the most stable lithium enolate isomer (3).
