title: VCD configuration of enantiopure/-enriched tetrasubstituted alpha-fluoro cyclohexanones and their use for epoxidation of trans-olefins.
abstract: The configurations of three enantiopure tetrasubstituted alpha-fluoro cyclohexanones (-)-5Ia, (-)-5IIa and (-)-6a were determined by VCD and proved to be (-)-(2S,5R)-5Ia, (-)-(2R,5R)-5IIa, and (-)-(2R,5R)-6a. The VCD study also identified the conformers populated in CDCl3 solution, including higher-energy gas-phase conformers with equatorial fluorine for 5Ia and 5IIa that are stabilized in CDCl3 solution. Used as catalysts for epoxidation of trans olefins (beta-methylstyrene, stilbene, methyl p-methoxy cinnamate) by oxone, it was found that (-)-5Ia is the most efficient for all trans olefins (providing, respectively, 62%, 90% and 66% ee) but that all three ketones provide high ee% with stilbene (78-90% ee). Moreover, the configurations predicted from the stereo outcome of the epoxidation reaction are identical to those determined by VCD.
authors.affiliation: Department of Chemistry, Syracuse University, Syracuse, New York, USA.
authors.forename: T B
authors.initials: TB
authors.lastname: Freedman
authors.forename: X
authors.initials: X
authors.lastname: Cao
authors.forename: L A
authors.initials: LA
authors.lastname: Nafie
authors.forename: A
authors.initials: A
authors.lastname: Solladié-Cavallo
authors.forename: L
authors.initials: L
authors.lastname: Jierry
authors.forename: L
authors.initials: L
authors.lastname: Bouerat