title: Characterization of beta-amino ester enolates as hexamers via 6Li NMR spectroscopy.
abstract: Low-temperature 6Li NMR spectroscopic studies on a chiral beta-amino ester enolate reveal a complex mixture of homo- and heterochiral aggregates. Subsequent warming of the samples led to rapid intra-aggregate exchange, resulting in four distinct resonances consistent with an ensemble of hexamers. An implicit fit of the aggregate populations to the Boltzmann distribution provided the free energy differences and equilibrium constants. An X-ray crystal structure obtained from the racemic enolate is consistent with the predominant aggregate in solution.
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA.
authors.forename: Anne J
authors.initials: AJ
authors.lastname: McNeil
authors.forename: Gilman E S
authors.initials: GE
authors.lastname: Toombes
authors.forename: Sithamalli V
authors.initials: SV
authors.lastname: Chandramouli
authors.forename: Benoit J
authors.initials: BJ
authors.lastname: Vanasse
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Ayers
authors.forename: Michael K
authors.initials: MK
authors.lastname: O'Brien
authors.forename: Emil
authors.initials: E
authors.lastname: Lobkovsky
authors.forename: Sol M
authors.initials: SM
authors.lastname: Gruner
authors.forename: John A
authors.initials: JA
authors.lastname: Marohn
authors.forename: David B
authors.initials: DB
authors.lastname: Collum
mesh_terms: D000478:Alkylation; D000605:Amino Alcohols / Q000737:chemistry*; D007202:Indicators and Reagents; D007554:Isotopes; D008094:Lithium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D013696:Temperature
chemical_list: D000605:Amino Alcohols; D007202:Indicators and Reagents; D007554:Isotopes; D008094:Lithium