title: Catalytic, asymmetric difluorination of alkenes to generate difluoromethylated stereocenters.
abstract: Difluoromethyl groups possess specific steric and electronic properties that invite their use as chemically inert surrogates of alcohols, thiols, and other polar functional groups important in a wide assortment of molecular recognition processes. We report here a method for the catalytic, asymmetric, migratory geminal difluorination of β-substituted styrenes to access a variety of products bearing difluoromethylated tertiary or quaternary stereocenters. The reaction uses commercially available reagents (m-chloroperbenzoic acid and hydrogen fluoride pyridine) and a simple chiral aryl iodide catalyst and is carried out readily on a gram scale. Substituent effects and temperature-dependent variations in enantioselectivity suggest that cation-π interactions play an important role in stereodifferentiation by the catalyst.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Banik
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Jonathan William
authors.initials: JW
authors.lastname: Medley
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA. jacobsen@chemistry.harvard.edu.
authors.forename: Eric N
authors.initials: EN
authors.lastname: Jacobsen