Chapter 21: Ester Enolates
Common Bases used to prepare enolates
The most common bases for preparing enolates are shown below:
General points to remember:
Hydroxide will cause
hydrolysis of esters
Alkoxide basses should match the alcohol part of an ester to avoid
NaH and LDA are usually used in tetrahydrofuran (THF) as the solvent (like many
NaH and LDA are strong bases.
Important things about LDA:
Strong base but poor nucleophile (too sterically hindered)
LDA is very good for making enolates of esters, aldehydes and ketones since it can give essentially 100% (quantitative conversion) to the enolate
This allows the enolate to be alkylated or acylated with less chance of self-condensation reactions.
Dr. Ian Hunt
, Department of Chemistry, University of Calgary