title: Functionalized tetrahydrofurans from alkenols and olefins/alkynes via aerobic oxidation-radical addition cascades.
abstract: Aerobic oxidation of alkyl- and phenyl-substituted 4-pentenols (bishomoallyl alcohols), catalyzed by cobalt(II) complexes in solutions of γ-terpinene or cyclohexa-1,4-diene, stereoselectively gave tetrahydrofurylmethyl radicals. Cyclized radicals were trapped with monosubstituted olefins (e.g., acrylonitrile, methyl acrylate), (E)- and (Z)-1,2-diacceptor-substituted olefins (e.g., dimethyl fumarate, fumarodinitrile, N-phenyl maleic imide), and ester-substituted alkynes (e.g., ethyl propynoate). Oxidation-addition cascades thus furnished side-chain-substituted (CN, CO(2)R, COR, or SO(2)R) di- and trisubstituted tetrahydrofurans in stereoselective reactions (2,3-trans, 2,4-cis, and 2,5-trans). A diastereomerically pure bistetrahydrofuran was prepared in a cascade consisting of two aerobic oxidations, one alkyne addition, and one final H-atom transfer.
authors.affiliation: Fachbereich Chemie, Organische Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Strasse, D-67663 Kaiserslautern, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Fries
authors.forename: Daniel
authors.initials: D
authors.lastname: Halter
authors.forename: Alexander
authors.initials: A
authors.lastname: Kleinschek
authors.forename: Jens
authors.initials: J
authors.lastname: Hartung