title: Regio- and stereoselective reactions of gem-difluorinated vinyloxiranes with heteronucleophiles.
abstract: [Reaction: see text]. Regio- and stereoselectivity in reactions of gem-difluorinated vinyloxiranes with heteronucleophiles were successfully controlled. Halogen atoms were introduced regioselectively at the allylic epoxide carbon with an inversion in stereochemistry using MgBr2*Et2O or Li2CuCl4 to produce anti-vic-halohydrine. The other diastereomers were obtained selectively using LiBr/AcOH or BCl3, and SN2' type products were formed selectively with excellent E preference by changing the reaction temperature. Moreover, a further investigation led us to find that a regio- and stereoselective SN2' addition of several Brnsted acids was dependent on the pKa values of the acids. Under strong acidic conditions, we exclusively obtained E allylic alcohols.
authors.affiliation: Graduate School of Bioscience and Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Hisanori
authors.initials: H
authors.lastname: Ueki
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kitazume
mesh_terms: D001089:Arabinose / Q000031:analogs & derivatives; D005027:Ethylene Oxide / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D018020:Lithium Compounds / Q000737:chemistry*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: C482965:3-deoxy-3,3-difluoro-D-arabinofuranose; D006845:Hydrocarbons, Fluorinated; D018020:Lithium Compounds; D001089:Arabinose; D005027:Ethylene Oxide