Diastereoselective Alkylation of β-Amino Esters: Structural
and Rate Studies Reveal Alkylations of Hexameric Lithium
Enolates
Anne J. McNeil
Gilman E. S. Toombes
Sol M. Gruner
Emil Lobkovsky
David B. Collum
Sithamalli V. Chandramouli
Benoit J. Vanasse
Timothy A. Ayers
10.1021/ja045144i.s001
https://acs.figshare.com/articles/journal_contribution/Diastereoselective_Alkylation_of_Amino_Esters_Structural_and_Rate_Studies_Reveal_Alkylations_of_Hexameric_Lithium_Enolates/3311161
Alkylation of β-amino ester enolates proceeds with high diastereoselectivity. Single crystal, powder,
and solution X-ray diffraction studies of the enolate show that the racemic enolate forms prismatic hexamers.
<sup>6</sup>Li NMR spectroscopic studies on partially racemic enolates reveal complex mixtures of homo- and
heterochiral hexamers. An implicit fit of the aggregate populations to the Boltzmann distribution provides
the free energy differences and equilibrium constants for the ensemble. Rate studies show that enolate
alkylation occurs directly from the hexamer with participation by THF. A mechanism based on the alkylation
of a ladder-like aggregate is proposed.
2004-12-22 00:00:00
Single crystal
rate studies show
THF
6 Li NMR spectroscopic studies
enolate show
heterochiral hexamers
racemic enolate forms prismatic hexamers
racemic enolates
energy differences
ester enolates proceeds
Boltzmann distribution
Diastereoselective Alkylation
Rate Studies Reveal Alkylations
enolate alkylation
equilibrium constants
Hexameric Lithium Enolates Alkylation