Efficient Iridium‐Catalyzed CH Functionalization/Silylation of Heteroarenes

Lu, Biao; Falck, John R.

doi:10.1002/ange.200802456

Cited by 55 publications

(3 citation statements)

References 38 publications

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“…[40][41][42] Traditional methods for the preparation of aryl-and heteroaryl-silanes involve the addition of organolithium or Grignard reagents to chlorosilanes or cyclosiloxanes, 43,44 transition-metal-catalyzed silyl substitution of halides, 45,46 and arene C-H silylation. 47,48 However drawbacks still existed. To this end, chemists are focusing their attention on exploiting novel routes for the synthesis of organosilicon compounds.…”

Section: Decarbonylative C-si Bond Forming Reactionsmentioning

confidence: 99%

Decarbonylative Cross-Couplings: Nickel Catalyzed Functional Group Interconversion Strategies for the Construction of Complex Organic Molecules

2018

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The utilization of carboxylic acid esters as electrophiles in metal-catalyzed cross-coupling reactions is increasingly popular, as environmentally friendly and readily available ester derivatives can be powerful alternatives to the commonly used organohalides. However, key challenges associated with the use of these chemicals remain to be addressed, including the stability of ester substrates and the high energy barrier associated with their oxidative addition to low-valent metal species. Due to recent developments in nickel catalysis that make it easier to perform oxidative additions, chemists have become interested in applying less reactive electrophiles as coupling counterparts in nickel-catalyzed transformations. Hence, our group and others have independently investigated various ester group substitutions and functionalizations enabled by nickel catalysis. Such methods are of great interest as they enable the exchange of ester groups, which can be used as directing groups in metal-catalyzed C-H functionalizations prior to their replacement. Here, we summarize our recent efforts toward the development of nickel-catalyzed decarbonylative cross-coupling reactions of carboxylic esters. Achievements accomplished by other groups in this area are also included. To this day, a number of new transformations have been successfully developed, including decarbonylative arylations, alkylations, cyanations, silylations, borylations, aminations, thioetherifications, stannylations, and hydrogenolysis reactions. These transformations proceed via a nickel-catalyzed decarbonylative pathway and have shown a high degree of reactivity and chemoselectivity, as well as several other unique advantages in terms of substrate availability, due to the use of esters as coupling partners. Although the mechanisms of these reactions have not yet been fully understood, chemists have already provided some important insights. For example, Yamamoto explored the stoichiometric nickel-mediated decarbonylation process of esters and proposed a reaction mechanism involving a C(acyl)-O bond cleavage and a CO extrusion. Key nickel intermediates were isolated and characterized by Shi and co-workers, supporting the assumption of a nickel/ N-heterocyclic carbene-promoted C(acyl)-O bond activation and functionalization. Our combined experimental and computational study of a ligand-controlled chemoselective nickel-catalyzed cross-coupling of aromatic esters with alkylboron reagents provided further insight into the reaction mechanism. We demonstrated that nickel complexes with bidentate ligands favor the C(aryl)-C bond cleavage in the oxidative addition step, resulting in decarbonylative alkylations, while nickel complexes with monodentate phosphorus ligands promote the activation of the C(acyl)-O bond, leading to the production of ketone products. Although more detailed mechanistic investigations need to be undertaken, the successful development of decarbonylative cross-coupling reactions can serve as a solid foundation for future studies. We believe that ...

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Section: Decarbonylative C-si Bond Forming Reactionsmentioning

confidence: 99%

Decarbonylative Cross-Couplings: Nickel Catalyzed Functional Group Interconversion Strategies for the Construction of Complex Organic Molecules

2018

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“…The reaction was catalyzed by the combination of [Ir(OMe)(cod)] 2 (cod = cycloocta-1,5-diene) with 4,4-di-tert-butyl-2,2-bipyridine (dtbpy) and 2norbornene as a hydrogen acceptor (Scheme 13). 27 Notably, the authors found that this catalyst system was also suitable for the ortho-selective silylation of S-and O-heteroarenes.…”

Section: Iridium-catalyzed Dehydrogenative Silylationsmentioning

confidence: 99%

Recent Advances in Transition-Metal-Catalyzed Silylations of Arenes with Hydrosilanes: C–X Bond Cleavage or C–H Bond Activation Synchronized with Si–H Bond Activation

et al. 2015

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Arylsilanes are valuable organosilicon compounds and attract significant research interest due to their promising applications in organic synthesis. The development of aromatic C-Si cross-coupling reactions represents a major challenge in both organosilicon chemistry and organic synthesis. A number of investigations are focused on developing transition-metal-catalyzed Si-C coupling reactions due to the associated high atom economy and superior functional group compatibility. This review describes recent advances in transition-metal-catalyzed selective silylations of aryl C-H and C-X (X = halide) bonds with hydrosilanes.

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“…1b ) 34 . In 2008, Falck and co-workers described an iridium-catalysed C–H silylation of N -unsubstituted indoles at the C2 position under mild condition using modest excess of Et 3 SiH reagent 35 . Similarly, in 2015, Stoltz and Grubbs reported a method to access C2-silylated indoles by KO t Bu-catalysed C–H silylation 36 , 37 .…”

Section: Introductionmentioning

confidence: 99%

Phosphorus(III)-assisted regioselective C–H silylation of heteroarenes

et al. 2021

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Heteroarenes containing carbon–silicon (C–Si) bonds are important building blocks that play an important role in the construction of natural products, pharmaceuticals, and organic materials. In this context, the C–H silylation of heteroarenes is a topic of intense interest. Indole C–H silylation can preferentially occur at the nucleophilic C3 and C2 position (pyrrole core), while accessing the C4-C7 positions (benzene core) of the indole remains highly challenging. Here, we show a general strategy for the regioselective C7-H silylation of indole derivatives. Mainly, the regioselectivity is determined by strong coordination of the palladium catalyst with phosphorus (III) directing group. Using this expedient synthetic strategy, the diverse C7-silylated indoles are synthesized effectively which exhibits the broad functional group compatibility. Moreover, this protocol also been extended to other heteroarenes such as carbazoles. The obtained silylated indoles have been employed in various transformations to enable the corresponding differently functionalized indole derivatives. Significantly, a cyclopalladated intermediate is successfully synthesized to test the hypothesis about the P(III)-directed C–H metalation event. A series of mechanistic experiments and density functional theory (M06-2X) calculations has shown the preferred pathway of this directed C–H silylation process.

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Efficient Iridium‐Catalyzed CH Functionalization/Silylation of Heteroarenes

Cited by 55 publications

References 38 publications

Decarbonylative Cross-Couplings: Nickel Catalyzed Functional Group Interconversion Strategies for the Construction of Complex Organic Molecules

Decarbonylative Cross-Couplings: Nickel Catalyzed Functional Group Interconversion Strategies for the Construction of Complex Organic Molecules

Recent Advances in Transition-Metal-Catalyzed Silylations of Arenes with Hydrosilanes: C–X Bond Cleavage or C–H Bond Activation Synchronized with Si–H Bond Activation

Phosphorus(III)-assisted regioselective C–H silylation of heteroarenes

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Efficient Iridium‐Catalyzed CH Functionalization/Silylation of Heteroarenes

Cited by 55 publications

References 38 publications

Decarbonylative Cross-Couplings: Nickel Catalyzed Functional Group Interconversion Strategies for the Construction of Complex Organic Molecules

Decarbonylative Cross-Couplings: Nickel Catalyzed Functional Group Interconversion Strategies for the Construction of Complex Organic Molecules

Recent Advances in Transition-Metal-Catalyzed Silylations of Arenes with Hydrosilanes: C–X Bond Cleavage or C–H Bond Activation­ Synchronized with Si–H Bond Activation

Phosphorus(III)-assisted regioselective C–H silylation of heteroarenes

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Recent Advances in Transition-Metal-Catalyzed Silylations of Arenes with Hydrosilanes: C–X Bond Cleavage or C–H Bond Activation Synchronized with Si–H Bond Activation