Mechanistic Studies of Copper(I)-Catalyzed 1,3-Halogen Migration

Hoveln, Ryan Van; Hudson, Brandi M.; Wedler, Henry B.; Bates, Desiree M.; Gros, Gabriel Le; Tantillo, Dean J.; Schomaker, Jennifer M.

doi:10.1021/ja511236d

Cited by 54 publications

(54 citation statements)

References 100 publications

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“…While the aryl copper intermediate could be observed, its instability and inability to form in appreciable quantities precluded a detailed investigation into its chemistry. 5 Thus, we were motivated by the potential for NHC-based catalysts to give well-defined intermediates for further studies.…”

Section: Introductionmentioning

confidence: 99%

Development of N-Heterocyclic Carbene–Copper Complexes for 1,3-Halogen Migration

et al. 2015

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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-bromo-and 2-chlorostyrenes through transfer of an aryl halogen to a benzylic carbon with concomitant arene borylation. The NHC-based system displays a broad substrate scope with notable advantages over previously reported phosphine-based catalysts, including complete selectivity for migration versus competing benzylic borylation, increased steric tolerance, efficient aryl chloride migration, and facile formation and characterization of organocopper catalytic intermediates. Experimental evidence and DFT calculations support a mechanism proceeding through dearomatization of a benzyl copper species, followed by a 1,4-halogen shift and borylation of the resulting ArCu(I) intermediate.

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Section: Introductionmentioning

confidence: 99%

Development of N-Heterocyclic Carbene–Copper Complexes for 1,3-Halogen Migration

et al. 2015

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“…[3,4] Very recently, the elegant work of Montgomery has expanded the scope of this transformation to simple styrenes. [5] A related borylative bromine recycling strategy was pioneered by Schomaker and coworkers, [6] which has been shown to proceed via a similar mechanism. [6d] Based on these precedents, we envisioned that the catalytic generation of a semibenzene intermediate ( III ) could serve as a generic platform for the development of a broad spectrum of novel rearrangement reactions, including the Cope rearrangement (Scheme 1).…”

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confidence: 99%

“…[5] A related borylative bromine recycling strategy was pioneered by Schomaker and coworkers, [6] which has been shown to proceed via a similar mechanism. [6d] Based on these precedents, we envisioned that the catalytic generation of a semibenzene intermediate ( III ) could serve as a generic platform for the development of a broad spectrum of novel rearrangement reactions, including the Cope rearrangement (Scheme 1). In contrast to conventionally applied strategies, this process utilizes aromatization as the crucial driving force for the rearrangement of these previously difficult-to-access dearomatized intermediates.…”

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Regio‐ and Stereospecific 1,3‐Allyl Group Transfer Triggered by a Copper‐Catalyzed Borylation/ortho‐Cyanation Cascade

Yang

2015

Angew Chem Int Ed

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A copper-catalyzed borylation/ortho-cyanation/allyl group transfer cascade has been developed. Initiated by an unconventional copper-catalyzed electrophilic dearomatization, this process features a regio- and stereospecific 1,3-transposition of the allyl fragment enabled by an aromatization-driven Cope rearrangement. This method provides an effective means for the construction of adjacent tertiary and quaternary stereocenters with excellent diastereocontrol.

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“…550 They suggested the ligated CuH complex 584 binds the olefin portion of the substrate to generate Cu/olefin complex 585 which undergoes a rate-determining hydrocupration to generate benzylic Cu(I) complex 586. This species can then directly react with HBPin via a σ-bond metathesis to form the undesired hydroboration product 587 551 or undergo a dearomative 1,3-Cu migration to leading to 588.…”

Section: Cu- Ag- and Au-catalyzed Reactionsmentioning

confidence: 99%

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

2016

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The high utility of halogenated organic compounds has prompted the development of a vast number of transformations which install the carbon-halogen motif. Traditional routes to these building blocks have commonly involved multiple steps, harsh reaction conditions, and the use of stoichiometric and/or toxic reagents. In this regard, using transition metals to catalyze the synthesis of organohalides has become a mature field in itself, and applying these technologies has allowed for a decrease in the production of waste, higher levels of regio- and stereoselectivity, and the ability to produce enantioenriched target compounds. Furthermore, transition metals offer the distinct advantage of possessing a diverse spectrum of mechanistic possibilities which translate to the capability to apply new substrate classes and afford novel and difficult-to-access structures. This Review provides comprehensive coverage of modern transition metal-catalyzed syntheses of organohalides via a diverse array of mechanisms. Attention is given to the seminal stoichiometric organometallic studies which led to the corresponding catalytic processes being realized. By breaking this field down into the synthesis of aryl, vinyl, and alkyl halides, it becomes clear which methods have surfaced as most favored for each individual class. In general, a pronounced shift toward the use of C-H bonds as key functional groups, in addition to methods which proceed by catalytic, radical-based mechanisms has occurred. Although always evolving, this field appears to be heading in the direction of using starting materials with a significantly lower degree of prefunctionalization in addition to less expensive and abundant metal catalysts.

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Mechanistic Studies of Copper(I)-Catalyzed 1,3-Halogen Migration

Cited by 54 publications

References 100 publications

Development of N-Heterocyclic Carbene–Copper Complexes for 1,3-Halogen Migration

Development of N-Heterocyclic Carbene–Copper Complexes for 1,3-Halogen Migration

Regio‐ and Stereospecific 1,3‐Allyl Group Transfer Triggered by a Copper‐Catalyzed Borylation/ortho‐Cyanation Cascade

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

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