Formal asymmetric hydrobromination of styrenes via copper-catalyzed 1,3-halogen migration
An enantioselective Cu(i)-catalyzed 1,3-halogen migration reaction accomplishes a formal hydrobromination by transferring a bromine activating group from a sp2 carbon to a benzylic carbon in good er and with concomitant borylation of the Ar-Br bond. Computational modelling aids in understanding the reaction outcome and suggests future directions to improve the formal asymmetric hydrobromination. The benzyl bromide can be displaced with a variety of nucleophiles to produce a wide array of functionalized products. This journal is
Development of N-Heterocyclic Carbene-Copper Complexes for 1,3-Halogen Migration
A series of NHC-copper complexes was synthesized and their potential to catalyze 1,3-halogen migration explored. Increasing the steric bulk around the metal drastically improves the lifetime of NHC-CuH species and promotes 1,3-halogen migration of both 2-
Schmid, Steven C.,Van Hoveln, Ryan,Rigoli, Jared W.,Schomaker, Jennifer M.
p. 4164 - 4173
(2015/09/01)
Mechanistic studies of copper(I)-catalyzed 1,3-halogen migration
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.
Van Hoveln, Ryan,Hudson, Brandi M.,Wedler, Henry B.,Bates, Desiree M.,Le Gros, Gabriel,Tantillo, Dean J.,Schomaker, Jennifer M.
supporting information
p. 5346 - 5354
(2015/05/13)
COPPER CATALYZED HALOGENATON AND REACTION PRODUCTS
A Cu(I)-catalyzed 1,3-halogen migration reaction effectively recycles an activating group by transferring a halogen from an sp2 to a benzylic carbon with good enantioselectivity and concomitant borylation of the Ar-halo bond. The resulting enantio-enriched benzyl halide can be reacted in the same vessel under a variety of conditions to form an additional carbon-heteroatom or carbon-carbon bond while maintaining high ee. The reaction can be used to efficiently prepare novel compounds and intermediates for the preparation of therapeutics and ligands for catalysis.
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Paragraph 0134
(2015/01/06)
Copper-catalyzed recycling of halogen activating groups via 1,3-halogen migration
A Cu(I)-catalyzed 1,3-halogen migration reaction effectively recycles an activating group by transferring bromine or iodine from a sp2 to a benzylic carbon with concomitant borylation of the Ar-X bond. The resulting benzyl halide can be reacted in the same vessel under a variety of conditions to form an additional carbon-heteroatom bond. Cross-over experiments using an isotopically enriched bromide source support intramolecular transfer of Br. The reaction is postulated to proceed via a Markovnikov hydrocupration of the o-halostyrene, oxidative addition of the resulting Cu(I) complex into the Ar-X bond, reductive elimination of the new sp3 C-X bond, and final borylation of an Ar-Cu(I) species to turn over the catalytic cycle.
Grigg, R. David,Van Hoveln, Ryan,Schomaker, Jennifer M.
supporting information
p. 16131 - 16134,4
(2020/09/09)
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