Abstract
The exceedingly high diastereoselectivity in Meyers' enolate alkylation has been interpreted using pyrrolidinone enolate anion (1 and 2) as the model. Recently, Meyers and Houk have proposed that torsional strain between reagent and β-hydrogen should control diastereo selectivity. We have investigated possible enolate isomers of this enolate system (2). It was found that selectivity is controlled by population of the most stable lithium enolate isomer (2-endo), FMO extension and accessible space (steric effect). The transition state between the bicyclic lactam (2) and MeBr using Gaussian 98 (2-endo-TS and 2-exo-TS) sugested that the torsional strain between the reagent (MeBr) and the β-hydrogen had no influence on diastereofacial selectivity.
