10.1021/ja992062z.s001
Xiufeng Sun
Xiufeng
Sun
David B. Collum
David B.
Collum
Lithium Diisopropylamide-Mediated Enolizations:
Solvent-Independent Rates, Solvent-Dependent Mechanisms
American Chemical Society
2000
HMPA
BuOMe
DMPU
disolvated monomers
monosolvated monomer
THF
solvation effects
tetrasolvated dimer
2000-03-02 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Lithium_Diisopropylamide-Mediated_Enolizations_Solvent-Independent_Rates_Solvent-Dependent_Mechanisms/3676059
Rate studies of a lithium diisopropylamide-mediated ester enolization reveal solvation effects that
are not in accord with expectation. Metalations in THF, <i>t</i>-BuOMe, HMPA/THF, and DMPU/THF (HMPA =
hexamethylphosphoramide, DMPU = 1,3-dimethyl-3,4,5,6-tetrahydro-2(1<i>H</i>)-pyrimidone) occur at nearly the
same rates, yet proceed via four fundamentally distinct scenarios: (1) disolvated monomer in THF, (2)
monosolvated dimer in <i>t</i>-BuOMe, (3) both monosolvated monomer and tetrasolvated dimer in HMPA/THF,
and (4) mono- and disolvated monomers in DMPU/THF. The implication of reactive open dimers in <i>t</i>-BuOMe
and triple ions in HMPA/THF underscores the importance of aggregate-based reactions.