Facile Catalytic SNAr Reaction of Nonactivated Fluoroarenes with Amines Using η6-Benzene Ruthenium(II) Complex

Otsuka, Maiko; Yokoyama, Hiroya; Endo, Kohei; Shibata, Takanori

doi:10.1055/s-0030-1258774

Cited by 10 publications

(6 citation statements)

References 2 publications

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“…Furthermore, benzylic alcohol reacted with fluorobenzene with 1a as a catalyst to form an alkyl−aryl-ether that can serve as a precursor to phenols. Concerning the mechanism, we propose that the reaction proceeds, similarly to reported arene exchange-based reactions, 23,42,43 via π-coordination of the fluoroarene, which enhances the electrophilicity and enables the S N Ar reaction with alcohols (Figure S67). The key intermediates of the catalytic cycle, namely, the fluoroarene complex (intermediate I in Figure S67) and alkyl-aryl-ether complex (intermediate II in Figure S67) have been individually detected by 1 H NMR spectroscopy and HRMS (Figures S68− S76).…”

Section: ■ Results and Discussionmentioning

confidence: 59%

Ruthenium Phenoxo Complexes: An Isolobal Ligand to Cp with Improved Properties

Schulte,

Wang,

et al. 2024

J. Am. Chem. Soc.

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Catalytic π-arene activation is based on catalysts that allow for arene exchange. To date, cyclopentadiene (Cp)-derived catalysts are the most commonly used in π-arene activation despite their low arene exchange rates. Herein, we report the synthesis, analysis, and catalytic application of Ru(II) complexes supported by phenoxo ligands, which are isolobal alternatives to Cp. The phenoxo complexes exhibit arene exchange rates significantly faster than those of the corresponding Cp complexes. The rate can be further increased through the choice of appropriate counterions. The mechanism of the arene exchange process is elucidated by kinetic and computational analyses. We demonstrate the utility of the new catalysts through an SNAr reaction between fluorobenzene and alcohols, including secondary alcohols that could not be used previously in related reactions. Moreover, the catalytic thermal decarboxylation of phenylacetic acids is presented.

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Section: ■ Results and Discussionmentioning

confidence: 59%

Ruthenium Phenoxo Complexes: An Isolobal Ligand to Cp with Improved Properties

Schulte,

Wang,

et al. 2024

J. Am. Chem. Soc.

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“…In follow up work by Shibata, ab ench stable catalyst[ Ru(h 6 -C 6 H 6 )Cl 2 ] 2 and an alternative phosphine ligand led to improvements in reaction efficiency,w ith yields > 80 %( Ta ble 1, Entry 3). [53] This reaction proceeded via intermediates 51 a and 51 b.…”

Section: Reactions Catalytic In Rutheniummentioning

confidence: 98%

“…Indeed an alternative catalyst, in which the DPPPent ligand in 50 b is replaced by two PPh 3 ligands gives comparable yields (72 % versus >99 % for 50 b ). In follow up work by Shibata, a bench stable catalyst [Ru(η 6 ‐C 6 H 6 )Cl 2 ] 2 and an alternative phosphine ligand led to improvements in reaction efficiency, with yields >80 % (Table 1, Entry 3) [53] . This reaction proceeded via intermediates 51 a and 51 b .…”

Section: Catalytic Transformations Via Transient η6‐coordinationmentioning

confidence: 99%

As Nice as π: Aromatic Reactions Activated by π‐Coordination to Transition Metals

Williams

Bhonoah

Wilkinson

et al. 2021

Chemistry A European J

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π‐Coordination of aromatic molecules to metals dramatically alters their reactivity. For example, coordinated carbons become more electrophilic and C−H bonds of coordinated rings become more acidic. For many years, this change in reactivity has been used to trigger reactions that would not take place for uncoordinated arenes, however, there has been a recent resurgence in use of this technique, in part due to the development of catalytic reactions in which π‐coordination is transient. In this Minireview, we describe the key reaction chemistry of arenes coordinated to a range of transition metals, including stereoselective reactions and industrially relevant syntheses. We also summarise outstanding examples of catalytic processes. Finally, we give perspectives on the future direction of the field, with respect to both reactions that are stoichiometric in activating metals and those employing catalytic metal.

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“…Shibata demonstrated the catalytic reactivity of a Ru(II) species bearing a PCP ligand, a design previously pioneered by Hartwig in the hydroamination of styrenes, in the amination of nonelectron-deficient aryl fluorides . Moreover, a monodentate phosphine P( p -FC 6 H 4 ) 3 was also shown to be efficient in the amination via a ruthenium η 6 -fluorobenzene complex bearing two phosphine ligands as the key intermediate . These reactions required the presence of 5 equiv of aryl fluorides, and the sluggish arene exchange was attributed to limited catalytic efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…9 Moreover, a monodentate phosphine P(p-FC 6 H 4 ) 3 was also shown to be efficient in the amination via a ruthenium η 6fluorobenzene complex bearing two phosphine ligands as the key intermediate. 10 These reactions required the presence of 5 equiv of aryl fluorides, and the sluggish arene exchange was attributed to limited catalytic efficiency. In 2020, a phosphine ligand featuring a weakly binding ether motif was shown to effect amination without the need for excess arenes.…”

Section: ■ Introductionmentioning

confidence: 99%

Ruthenium/η⁵-Phenoxo-Catalyzed Amination of Phenols with Amines

Chen,

Ma,

Lin

et al. 2024

J. Am. Chem. Soc.

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Ruthenium(II) complexes are known to form η6-arene complexes with benzene-containing compounds through π-coordination, a property extensively utilized to initiate reactions not typically observed with free arenes. A prime example is nucleophilic aromatic substitution, where ruthenium-complexed aryl halides undergo nucleophilic attack, allowing the direct synthesis of diverse aromatic compounds by displacing halides with nucleophiles. However, this activation relies on the electron-withdrawing effect of the Ru(II) species, as well as is hindered by the resistance of η6-arenes to arene exchange. In the previous pursuit of catalysis, the emphasis of ligand design has centered on promoting arene exchange. In this study, we extended the ruthenium activation strategy to umpolung substitution reactions of phenols. The amination proceeds through a direct condensation between phenols and amines, with a key intermediate identified as [bis(η5-phenoxo)Ru], which is in situ generated from a commercially available ruthenium catalyst. In comparison with the well-studied cyclopentadienyl (Cp) type ligands, we demonstrated that an η5-phenoxo motif, as a superior alternative to Cp, contributes to the amination of phenols in two crucial ways: its less electron-donating nature enhances the withdrawing effect of the ruthenium unit, facilitating substitution on the phenol complex; its distinctive behavior in arene exchange allows for conducting the amination with a catalytic amount of metal. Additionally, hydrogen bonding, wherein the phenoxo serves as the acceptor, was found to be important for the substitution. The versatility of this ruthenium-catalyzed amination was validated by performing reactions with a diverse array of phenols exhibiting various electronic properties, in combination with a wide range of primary amines. This work exemplifies the expansion of the scope of π-coordination activation in catalysis through innovative ligand development.

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Facile Catalytic SNAr Reaction of Nonactivated Fluoroarenes with Amines Using η6-Benzene Ruthenium(II) Complex

Cited by 10 publications

References 2 publications

Ruthenium Phenoxo Complexes: An Isolobal Ligand to Cp with Improved Properties

Ruthenium Phenoxo Complexes: An Isolobal Ligand to Cp with Improved Properties

As Nice as π: Aromatic Reactions Activated by π‐Coordination to Transition Metals

Ruthenium/η⁵-Phenoxo-Catalyzed Amination of Phenols with Amines

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Facile Catalytic SNAr Reaction of Nonactivated Fluoroarenes with Amines Using η6-Benzene Ruthenium(II) Complex

Cited by 10 publications

References 2 publications

Ruthenium Phenoxo Complexes: An Isolobal Ligand to Cp with Improved Properties

Ruthenium Phenoxo Complexes: An Isolobal Ligand to Cp with Improved Properties

As Nice as π: Aromatic Reactions Activated by π‐Coordination to Transition Metals

Ruthenium/η5-Phenoxo-Catalyzed Amination of Phenols with Amines

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Ruthenium/η⁵-Phenoxo-Catalyzed Amination of Phenols with Amines