Origin of stereochemistry in Meyers enolate alkylations. Importance of major enolate structure and population in tetrahydrofuran

It was found that in tetrahydrofuran solution, predominance (99.2%) of the highly stabilized Meyers enolate (1,5-dimethylpyrrolidin-2-one lithium enolate (1)) isomer with intramolecular Li-πCC coordination from the endo-face (Ct-endo) may be responsible for exceedingly high endo-selectivity in Meyers enolate alkylation.