title: Preparation and regioselective SN2' reaction of novel gem-difluorinated vinyloxiranes with RLi.
abstract: A series of hitherto unknown 3,4-epoxy-1,1-difluorobutenes were prepared from the readily accessible alpha,beta-epoxy ketones and these compounds were found to undergo regioselective S(N)2' reactions with hard RLi nucleophiles occurring at the highly positively charged terminal fluorine-possessing sp(2) carbon atom in quite sharp contrast to the cases of the corresponding nonfluorinated vinyloxiranes which only attained a low level of regioselectivity. Addition of HMPA substantially improved the products' olefinic stereoselectivity. Theoretical calculations were used to qualitatively explore the nature of selectivity in these reactions.
authors.affiliation: Graduated School of Bioscience and Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8510, Japan.
authors.forename: Hisanori
authors.initials: H
authors.lastname: Ueki
authors.forename: Takashi
authors.initials: T
authors.lastname: Chiba
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kitazume