title: Synthesis and Utilization of Trialkylammonium-Substituted Cyclodextrins as Water-Soluble Chiral NMR Solvating Agents for Anionic Compounds.
abstract: Cationic trialkylammonium-substituted α-, β-, and γ-cyclodextrins containing trimethyl-, triethyl-, and tri-n-propylammonium substituent groups were synthesized and analyzed for utility as water-soluble chiral nuclear magnetic resonance (NMR) solvating agents. Racemic and enantiomerically pure (3-chloro-2-hydroxypropyl)trimethyl-, triethyl-, and tri-n-propyl ammonium chloride were synthesized from the corresponding trialkyl amine hydrochloride and either racemic or enantiomerically pure epichlorohydrin. The ammonium salts were then reacted with α-, β-, and γ-cyclodextrins at basic pH to provide the corresponding randomly substituted cationic cyclodextrins. The (1) H NMR spectra of a range of anionic, aromatic compounds was recorded with the cationic cyclodextrins. Cyclodextrins with a single stereochemistry at the hydroxy group on the (2-hydroxypropyl)trialkylammonium chloride substituent were often but not always more effective than the corresponding cyclodextrin in which the C-2 position was racemic. In several cases, the larger triethyl or tri-n-propyl derivatives were more effective than the corresponding trimethyl derivative at causing enantiomeric differentiation. None of the cyclodextrin derivatives were consistently the most effective for all of the anionic compounds studied.
authors.affiliation: Department of Chemistry, Bates College, Lewiston, Maine, USA.
authors.forename: Alison E
authors.initials: AE
authors.lastname: Dowey
authors.affiliation: Department of Chemistry, Bates College, Lewiston, Maine, USA.
authors.forename: Cira Mollings
authors.initials: CM
authors.lastname: Puentes
authors.affiliation: Department of Chemistry, Bates College, Lewiston, Maine, USA.
authors.forename: Mira
authors.initials: M
authors.lastname: Carey-Hatch
authors.affiliation: Department of Chemistry, Bates College, Lewiston, Maine, USA.
authors.forename: Keyana L
authors.initials: KL
authors.lastname: Sandridge
authors.forename: Nikhil B
authors.initials: NB
authors.lastname: Krishna
authors.affiliation: Department of Chemistry, Bates College, Lewiston, Maine, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Wenzel
keywords: NMR; chiral analysis; chiral solvating agents; cyclodextrins; enantiomeric differentiation