title: Absolute Configuration and Conformation of Two Fráter-Seebach Alkylation Reaction Products by Film VCD and ECD Spectroscopic Analyses.
abstract: Two chiroptical spectroscopic techniques, namely, electronic and vibrational circular dichroism (ECD and VCD), as well as NMR spectroscopy have been utilized to determine the absolute configurations and geometries of two Fráter-Seebach alkylation reaction products with long hydrocarbon chains. The experimental studies have been complemented with density functional theory calculations. Strong characteristic bisignate VCD signatures in the carbonyl stretching region have been observed for both compounds in film state. Truncated models, i.e., without the long CH2 chains, have been utilized to examine different hydrogen-bonding topologies between two monomeric moieties and to simulate the corresponding IR and VCD spectra of the dimers. In addition, the exciton coupling model has also been applied to the -C═O groups of the two monomeric moieties, which can be coupled through intermolecular hydrogen-bonding. On the basis of these simplified approaches, the absolute configurations of the compounds have been unambiguously assigned using VCD and ECD spectroscopy. Spectral simulations in the IR and UV-vis regions have also been carried out with the full dimers to validate the fitness of the truncated model. The study shows that the combination of the film VCD and ECD techniques is a relatively straightforward method to determine the absolution configurations of such synthetic compounds.
authors.affiliation: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Poopari
authors.affiliation: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Dezhahang
authors.affiliation: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Ke
authors.initials: K
authors.lastname: Shen
authors.affiliation: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Todd L
authors.initials: TL
authors.lastname: Lowary
authors.affiliation: Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Xu