Dual Role of Rh(III) Catalyst Enables Regioselective Halogenation of (Electron-Rich) Heterocycles

Schröder, Nils; Lied, Fabian; Glorius, Frank

doi:10.1021/jacs.5b00283

Cited by 123 publications

(65 citation statements)

References 62 publications

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“…In aseries of experiments,the catalyst loading was decreased while increasing the reaction time to elucidate the maximum TONofthe cobalt catalyst in this transformation. [54] Thes tandard conditions of this transformation utilize 2mol %o ft he precatalyst [Cp*Rh(MeCN) 3 ]-(SbF 6 ) 2 .A ne ven more efficient reaction was developed by analysis of the reaction mechanism, revealing as econdary role of the rhodium catalyst as halide scavenger.W hile this role suppresses the uncatalyzed electrophilic halogenation of the substrate,i talso deactivates the rhodium catalyst for the desired directed halogenation. Af urther study indicated that pyrimidyl indoles might be privileged substrates for the exceptional efficiencyo ft his transformation, as other substrates required ah igher catalyst loading of 5mol %[ Co] to promote conversion.…”

Section: Palladium Catalysismentioning

confidence: 99%

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Increasing Catalyst Efficiency in C−H Activation Catalysis

et al. 2018

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C-H activation reactions with high catalyst turnover numbers are still very rare in the literature and 10 mol % is a common catalyst loading in this field. We offer a representative overview of efficient C-H activation catalysis to highlight this neglected aspect of catalysis development and inspire future effort towards more efficient C-H activation. Examples ranging from palladium catalysis, Cp*Rh - and Cp*Co -catalysis, the C-H borylation and silylation to methane C-H activation are presented. In these reactions, up to tens of thousands of catalyst turnovers have been observed.

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Section: Palladium Catalysismentioning

confidence: 99%

“…Rhodium-catalyzed alkyne annulations. [54] Angewandte Chemie Suzuki-Miyaura cross-coupling. Rh-catalyzed CÀHolefination with an oxidizing directing group.…”

Section: Ir- Rh- and Ru-catalyzed C à Hb Orylation And Silylationmentioning

confidence: 99%

Increasing Catalyst Efficiency in C−H Activation Catalysis

et al. 2018

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“…239 This reaction was found to override the inherent selectivity of these heteroaryl substrates to undergo an uncatalyzed halogenation at the 5 position, in contrast to the 3-position in the Rh(III)-catalyzed process (Scheme 115).…”

Section: Co-and Rh-catalyzed Synthesis Of Aryl Halidesmentioning

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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“…Major progress in CÀHh alogenation was achieved by using various electrophilic halogenating reagents,although in afew cases ad ihalogen (e.g.I 2 )w as used as the halogen source. [161] Ak ey aspect of this reaction is that it permits the undesired halogenation of heterocycles at other positions to be suppressed. [160] Theeffect of various other directing groups on this reaction was also examined.…”

Section: Halogenationmentioning

confidence: 99%

Rhodium‐Catalyzed C(sp²)‐ or C(sp³)−H Bond Functionalization Assisted by Removable Directing Groups

2019

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In recent years, transition‐metal‐catalyzed C−H activation has become a key strategy in the field of organic synthesis. Rhodium complexes are widely used as catalysts in a variety of C−H functionalization reactions because of their high reactivity and selectivity. The availability of a number of rhodium complexes in various oxidation states enables diverse reaction patterns to be obtained. Regioselectivity, an important issue in C−H activation chemistry, can be accomplished by using a directing group to assist the reaction. However, to obtain the target functionalized compounds, it is also necessary to use a directing group that can be easily removed. A wide range of directed C−H functionalization reactions catalyzed by rhodium complexes have been reported to date. In this Review, we discuss Rh‐catalyzed C−H functionalization reactions that are aided by the use of a removable directing group such as phenol, amine, aldehyde, ketones, ester, acid, sulfonic acid, and N‐heteroaromatic derivatives.

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Dual Role of Rh(III) Catalyst Enables Regioselective Halogenation of (Electron-Rich) Heterocycles

Cited by 123 publications

References 62 publications

Increasing Catalyst Efficiency in C−H Activation Catalysis

Increasing Catalyst Efficiency in C−H Activation Catalysis

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

Rhodium‐Catalyzed C(sp²)‐ or C(sp³)−H Bond Functionalization Assisted by Removable Directing Groups

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Dual Role of Rh(III) Catalyst Enables Regioselective Halogenation of (Electron-Rich) Heterocycles

Cited by 123 publications

References 62 publications

Increasing Catalyst Efficiency in C−H Activation Catalysis

Increasing Catalyst Efficiency in C−H Activation Catalysis

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

Rhodium‐Catalyzed C(sp2)‐ or C(sp3)−H Bond Functionalization Assisted by Removable Directing Groups

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Rhodium‐Catalyzed C(sp²)‐ or C(sp³)−H Bond Functionalization Assisted by Removable Directing Groups