<i>O</i>-Directed C–H functionalization <i>via</i> cobaltacycles: a sustainable approach for C–C and C–heteroatom bond formations

Banjare, Shyam Kumar; Nanda, Tanmayee; Pati, Bedadyuti Vedvyas; Biswal, Pragati; Ravikumar, Ponneri C.

doi:10.1039/d0cc08199j

Cited by 33 publications

(20 citation statements)

References 139 publications

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“…Over the past few years, some reviews on 3d metal-catalyzed C–H bond activation reactions were documented. However, to the best of our knowledge, there is no review that explicitly highlights the importance of weakly coordinating directing groups in C–H bond activation with 3d metal catalysts . Considering the growing interest in utilizing functional groups that are present in a molecule as weakly coordinating directing groups for C–H bond functionalizations, we sought to provide a comprehensive overview on the topic covering articles until 2021.…”

Section: Introductionmentioning

confidence: 99%

Weak-Coordination in C–H Bond Functionalizations Catalyzed by 3d Metals

2022

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Transition-metal-catalyzed C–H bond functionalizations have had an enormous influence on organic synthesis in recent times. However, the use of low-abundance 4d and 5d metals is almost inevitable, and they are in high demand. This will be a cause of concern, and hence, it is important to develop methods based on 3d metals, which are widely present in the Earth’s crust. In this regard, the use of 3d metal catalysts or their precursors for catalysis, in general, and C–H bond functionalizations, in particular, has gained significant momentum in the recent times. The major development in catalytic C–H bond functionalizations with 3d metals has been achieved predominantly with strongly coordinating directing groups such as pyridyl, pyrimidinyl, pyrazolyl, and 8-amino-quinolinyl groups. Thus, prefunctionalization of substrates with these directing groups is necessary, which contradicts the step- and atom-economy of C–H bond activation. However, commonly available functional groups such as aldehyde, ketone, carboxylic acid, amide, hydroxy, and N-oxides loosely bind to metals through weak-coordination. These weakly coordinating directing groups orient the metal to activate C–H bond regioselectively without the need for preinstalled strongly coordinating directing groups. Although it is challenging, this contemporary topic has been actively pursued by many researchers in recent times. Through this article, we provide a comprehensive overview of 3d metal-catalyzed, weakly coordinating, directing-group-enabled C–H bond functionalizations reported until March 2021.

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Section: Introductionmentioning

confidence: 99%

Weak-Coordination in C–H Bond Functionalizations Catalyzed by 3d Metals

2022

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“…Cobalt’s ability to mimic rhodium in reactivity and selectivity has brought huge success to various pioneering research groups . Though cobalt-catalyzed C–H activation with a variety of N -coordinating directing groups (strong coordination) were well studied, only limited reports are available on exploiting the O -coordinating ability (weak coordination) of commonly prevailing directing groups such as aldehyde, ketone, ester, carboxylic acid, etc . This provides an eccentric opportunity to fine-tune the combination of “cobalt-weak coordination” to address the previous issues.…”

Section: Introductionmentioning

confidence: 99%

Breaking the Trend: Insight into Unforeseen Reactivity of Alkynes in Cobalt-Catalyzed Weak Chelation-Assisted Regioselective C(4)–H Functionalization of 3-Pivaloyl Indole

et al. 2021

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Unique reactivity of diphenylacetylene has been uncovered through weak chelation-assisted cobalt-catalyzed regioselective C(4)–H activation of 3-pivolyl indole. α-Hydroxy ketone and α,β-unsaturated ketone derivatives have been synthesized in good yields from indole and alkynes. Notably, the indole C(4)–H-functionalized α,β-unsaturated ketone product was obtained with high stereo- and regioselectivity simply by changing the coupling partner from symmetrical alkynes to unsymmetrical aromatic-aliphatic alkynes. Most importantly, trifluoroethanol acts as a sole source of water for this conversion. Quantitative detection of bis(2,2,2-trifluoroethyl) ether from dry trifluoroethanol through 19F NMR and LCMS studies indirectly confirms the in situ formation of water. A six-membered cobaltacycle intermediate was detected in HRMS, and also, this was further confirmed by the quantum mechanical calculations, which accounts for the highly regioselective C(4)–H functionalization.

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“…). 2 Catalysed by transition metals, C–N bond building reactions are of particular importance in biology, pharmaceuticals and materials science. 3 There are many examples of C–N bond formation reactions using organic (pseudo) halides such as aryl iodides, bromides, chlorides, triflates and sulfonates, that react with amines or their precursors.…”

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confidence: 99%

Acetonitrile and benzonitrile as versatile amino sources in copper-catalyzed mild electrochemical C–H amidation reactions

et al. 2021

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O-Directed C–H functionalization via cobaltacycles: a sustainable approach for C–C and C–heteroatom bond formations

Abstract: This review focuses on providing comprehensive highlights of the recent advances in the field of cobalt-catalysed C−H functionalization and related synthetic concepts relying on these through oxygen atom coordination. In...

Cited by 33 publications

References 139 publications

Weak-Coordination in C–H Bond Functionalizations Catalyzed by 3d Metals

Weak-Coordination in C–H Bond Functionalizations Catalyzed by 3d Metals

Breaking the Trend: Insight into Unforeseen Reactivity of Alkynes in Cobalt-Catalyzed Weak Chelation-Assisted Regioselective C(4)–H Functionalization of 3-Pivaloyl Indole

Acetonitrile and benzonitrile as versatile amino sources in copper-catalyzed mild electrochemical C–H amidation reactions

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