title: Regioselective Synthesis of α,α-Difluorocyclopentanone Derivatives: Domino Nickel-Catalyzed Difluorocyclopropanation/Ring-Expansion Sequence of Silyl Dienol Ethers.
abstract: Silyl dienol ethers prepared from α,β-unsaturated ketones underwent nickel-catalyzed difluorocyclopropanation of the electron-rich alkene moiety with trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate. The subsequent vinylcyclopropane-cyclopentene rearrangement afforded silyl 5,5-difluorocyclopent-1-en-1-yl ethers in good yields. The obtained five-membered silyl enol ethers were demonstrated to be versatile intermediates for the synthesis of di- and monofluorinated cyclopentanones and cyclopentenones. A nickel difluorocarbene complex is proposed as a key intermediate in the difluorocyclopropanation.
authors.affiliation: Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Aono
authors.affiliation: Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Sasagawa
authors.affiliation: Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fuchibe
authors.affiliation: Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba , Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Ichikawa