Mechanistic Studies of Copper(I)-Catalyzed 1,3-Halogen Migration
2015
Van Hoveln, Ryan | Hudson, Brandi M. | Wedler, Henry B. | Bates, Desiree M. | Le Gros, Gabriel | Tantillo, Dean J. | Schomaker, Jennifer M.
An ongoing challenge in modern catalysis is to identify and understand new modes of reactivity promoted by earth-abundant and inexpensive first-row transition metals. Herein, we report a mechanistic study of an unusual copper(I)-catalyzed 1,3-migration of 2-bromostyrenes that reincorporates the bromine activating group into the final product with concomitant borylation of the aryl halide bond. A combination of experimental and computational studies indicated this reaction does not involve any oxidation state changes at copper; rather, migration occurs through a series of formal sigmatropic shifts. Insight provided from these studies will be used to expand the utility of aryl copper species in synthesis and develop new ligands for enantioselective copper-catalyzed halogenation.
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