Solution Structures and Reactivities of the Mixed Aggregates Derived from n-Butyllithium and Vicinal Amino Alkoxides
- 31 July 2001
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 123 (33) , 8039-8046
- https://doi.org/10.1021/ja010136c
Abstract
Low-temperature (6)Li, (13)C, and (15)N NMR spectroscopies reveal that mixtures of n-BuLi and (1R,2S)-R'(2)NCH(R)CH(Ph)OLi (ROLi; R = Ph or Me; R'(2)N = pyrrolidino or Me(2)N) in THF/pentane afford a (n-BuLi)(3)(ROLi) (3:1) mixed tetramer and a C(2)-symmetric (n-BuLi)(2)(ROLi)(2) (2:2) mixed tetramer depending on the proportions of the reactants. The corresponding (n-BuLi)(ROLi)(3) (1:3) mixed tetramer is not observed. ROLi-mediated additions of n-BuLi to benzaldehyde proceed with up to 21:1 enantiomeric ratios that depend on the n-BuLi/ROLi stoichiometries. The enantioselectivities are considered in light of a previously posited mechanism involving reaction via the C(2)-symmetric 2:2 mixed tetramer.Keywords
This publication has 33 references indexed in Scilit:
- Highly Enantioselective 1,2-Addition of Lithium Acetylide-Ephedrate Complexes: Spectroscopic Evidence for Reaction Proceeding via a 2:2 Tetramer, and X-ray Characterization of Related ComplexesJournal of the American Chemical Society, 2000
- New Dodecameric n-Propyllithium/Lithium n-Propoxide Mixed Aggregate. Evidence for the First Cuboctahedral Lithium AggregateJournal of the American Chemical Society, 1999
- Lithium Ephedrate-Mediated Addition of a Lithium Acetylide to a Ketone: Solution Structures and Relative Reactivities of Mixed Aggregates Underlying the High EnantioselectivitiesJournal of the American Chemical Society, 1998
- Probing the Origins of Asymmetric Induction by 3-Aminopyrrolidine Lithium Amides Complexes: A 6Li/1H/13C NMR StudyJournal of the American Chemical Society, 1997
- Stereogenic Lithium Centers in a Complex between n-Butyllithium and a Dilithiated Chiral Amine: Solution Studies by 6Li,1H-HOESY, 6Li,6Li-COSY, and 6Li,6Li-EXSY NMROrganometallics, 1995
- 6Li-15N heteronuclear multiple quantum correlation (HMQC) spectroscopy: Application to the structure determination of lithium 2,2,6,6-tetramethylpiperidide mixed aggregatesMagnetic Resonance in Chemistry, 1992
- Structural and energetic evidence for oxygen-lithium-nitrogen chelation in a model for asymmetric inductionJournal of the American Chemical Society, 1990
- Isotope effects in nucleophilic substitution reactions. VI. The effect of ion pairing on the transition state structure of SN2 reactionsCanadian Journal of Chemistry, 1988
- Electron density analysis of the reaction of aldehydes with lithium hydride. The general importance of the HOMO-HOMO interactionJournal of the American Chemical Society, 1986
- A convenient method for estimation of alkyllithium concentrationsThe Journal of Organic Chemistry, 1976