Chapter 21: Ester Enolates
The Dieckmann Condensation
Reaction type : Intramolecular Nucleophilic Acyl Substitution
Summary
Diester compounds can be used to give an
intramolecular
Claisen condensation
which is known as the
Dieckmann condensation
.
This means the
enolate component
and the
carbonyl component
are parts of a single, larger molecule.
Reagents : most commonly the base would be the alkoxide,
RO
-
, matching the alcohol portion of the ester (
why ?
)
Remember enolates are good nucleophiles and the ester carbonyl
C
are electrophilic.
The products of these reactions are cyclic
b-
ketoesters which are
important, useful synthetic intermediates
Favours the formation of the more stable 5- or 6-membered rings (
review
)
How can you deduce this product ?
Form the enolate (there two possible equivalent enolates either at C2 or C5)
Make the enolate attack the other carbonyl.
STUDY TIP
:
When doing intramolecular reactions, it is a good idea to count carbon atoms to help avoid silly errors.
Related Reactions
Claisen Condensation
Intramolecular Aldol Condensations
