A multinuclear magnetic resonance investigation, supported by density functional theory calculations. has been synergically used to investigate the configurational stability, reactivity and aggregation states of alpha-lithiated styrene oxide in THF at 173 K. NMR studies on alpha-lithiated [alpha,beta-C-13(2)]styrene oxide (also in an enantiomerically enriched form) proved that in THF this oxiranyllithium is mainly present as a solvated monomeric species in equilibrium with a complex mixture of stereoisomeric dimeric aggregates, as well as with bridged and tetrameric aggregates. The fact that some C-alpha-Li bonds are partially broken in some stereoisomers reduces their symmetry and complicates the NMR spectra: two diastereoisomers each having a pair of diastereotopic carbon atoms slowly inverting at the lithium aloin in absence of tetramethylethylenediamine (TMEDA) have been detected. A (C-13, Li-7)-HMQC experiment to correlate Li-7 and C-13 resonances of the Various aggregates has bee...
Capriati, V., Florio, S., Perna, F., Salomone, A., Abbotto, A., Amedjkouh, M., et al. (2009). On the dichotomic reactivity of lithiated styrene oxide: A computational and multinuclear magnetic resonance investigation. CHEMISTRY-A EUROPEAN JOURNAL, 15(32), 7958-7979 [10.1002/chem.200900834].
On the dichotomic reactivity of lithiated styrene oxide: A computational and multinuclear magnetic resonance investigation
ABBOTTO, ALESSANDRO;
2009
Abstract
A multinuclear magnetic resonance investigation, supported by density functional theory calculations. has been synergically used to investigate the configurational stability, reactivity and aggregation states of alpha-lithiated styrene oxide in THF at 173 K. NMR studies on alpha-lithiated [alpha,beta-C-13(2)]styrene oxide (also in an enantiomerically enriched form) proved that in THF this oxiranyllithium is mainly present as a solvated monomeric species in equilibrium with a complex mixture of stereoisomeric dimeric aggregates, as well as with bridged and tetrameric aggregates. The fact that some C-alpha-Li bonds are partially broken in some stereoisomers reduces their symmetry and complicates the NMR spectra: two diastereoisomers each having a pair of diastereotopic carbon atoms slowly inverting at the lithium aloin in absence of tetramethylethylenediamine (TMEDA) have been detected. A (C-13, Li-7)-HMQC experiment to correlate Li-7 and C-13 resonances of the Various aggregates has bee...
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