Effect of solvent on aggregation and reactivity of two lithium enolates

[GRAPHICS] Studies with two lithium enolates show that aggregation varies from compara ble to lower in dimethoxyethane (DME) compared to tetrahydrofuran (THF) but that aggregation is much higher in methyl tert-butyl ether (MTBE), Alkylat ion reactions, which occur dominantly with the enolate monomers, are except ionally slow in MTBE, but even acylation reactions that can occur with aggr egates are orders of magnitude slower in MTBE. These reactions apparently r equire additional solvation of the lithium cation, and MTBE is ineffective at such solvation.