Insight into the Behaviour of a Lithium
Enolate in Solution
tert-Butyloxodioxolaneacetic acid was dilithiated to the enolate
with LDA, then treated with MeCO2D, and finally with
CH2N2 to give the deuterated
ester. Two different stable forms of the enolate were produced, depending
on whether the deprotonation of was carried out in toluene or in THF. The
generated (Me2CH)2NH was coordinated
to the enolate and, hence, served as a strong lipophilic solvating agent.
LDA could substitute the amine ligands of the two species to a different
extent. THF was partially able to displace (Me2CH)2NH
in toluene, but the coordination of the amine to the enolate produced in
THF was quantitative.

