title: Nickel-catalyzed regiodivergent opening of epoxides with aryl halides: co-catalysis controls regioselectivity.
abstract: Epoxides are versatile intermediates in organic synthesis, but have rarely been employed in cross-coupling reactions. We report that bipyridine-ligated nickel can mediate the addition of functionalized aryl halides, a vinyl halide, and a vinyl triflate to epoxides under reducing conditions. For terminal epoxides, the regioselectivity of the reaction depends upon the cocatalyst employed. Iodide cocatalysis results in opening at the less hindered position via an iodohydrin intermediate. Titanocene cocatalysis results in opening at the more hindered position, presumably via Ti(III)-mediated radical generation. 1,2-Disubstituted epoxides are opened under both conditions to form predominantly the trans product.
authors.affiliation: Department of Chemistry, University of Rochester , Rochester, New York, United States 14627-0216.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Weix
mesh_terms: D002384:Catalysis; D004852:Epoxy Compounds / Q000737:chemistry*; D006219:Halogens / Q000737:chemistry*; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry
chemical_list: D004852:Epoxy Compounds; D006219:Halogens; D009930:Organic Chemicals; D009532:Nickel; D014025:Titanium