N-substituted aminobiphenyl palladacycles stabilized by dialkylterphenyl phosphanes: Preparation and applications in C N cross-coupling reactions

Monti, Andrea; Rama, Raquel J.; Vélez-Gómez, Beatriz; Maya, Celia; Álvarez, Eleuterio; Carmona, Ernesto; Nicasio, M. Carmen

doi:10.1016/j.ica.2020.120214

Cited by 7 publications

(3 citation statements)

References 53 publications

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“…Other examples of Buchwald–Hartwig indole N -arylation include the use of the ligands F4-1 [ 81 ], F4-2 [ 82 ], and t BuXphos ( F4-3 ) [ 83 ] ( Figure 4 ). In addition, the palladium-catalyzed amination of triflates [ 84 , 85 ]; cross-coupling reactions of silylated indoles with aryl halides [ 86 , 87 ]; and reactions that are catalyzed by Pd/ZnO nanoparticles [ 88 ], palladium immobilized on graphene [ 89 ], or silica-starch substrates [ 90 ] were used to prepare N -arylindoles.…”

Section: Transition-metal-catalyzed N -Arylation Of Indolesmentioning

confidence: 99%

Recent Progress Concerning the N-Arylation of Indoles

et al. 2021

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This review summarizes the current state-of-the-art procedures in terms of the preparation of N-arylindoles. After a short introduction, the transition-metal-free procedures available for the N-arylation of indoles are briefly discussed. Then, the nickel-catalyzed and palladium-catalyzed N-arylation of indoles are both discussed. In the next section, copper-catalyzed procedures for the N-arylation of indoles are described. The final section focuses on recent findings in the field of biologically active N-arylindoles.

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Section: Transition-metal-catalyzed N -Arylation Of Indolesmentioning

confidence: 99%

Recent Progress Concerning the N-Arylation of Indoles

et al. 2021

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“…Recently, we examined the behavior of a family of dialkylterphenyl phosphines − in Pd-catalyzed aryl amination reactions using 2-aminobiphenyl-derived palladacycles as precatalysts. , We found that the cationic palladacycle with the sterically demanding phosphine PCyp 2 Ar Xyl2 , P1 (Scheme ), displayed excellent performance and provided a broader substrate scope in the amination of deactivated aryl chlorides with N -nucleophiles, including primary and secondary alkyl and arylamines and N -heterocycles such as indoles (Table ). To understand the reasons for the high activity and broad applicability of palladacycle P1 , we decided to investigate the mechanism of aryl amination reactions catalyzed by P1 , including the precatalyst activation step, by experiments and calculations.…”

Section: Introductionmentioning

confidence: 99%

Important Role of NH-Carbazole in Aryl Amination Reactions Catalyzed by 2-Aminobiphenyl Palladacycles

et al. 2023

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2-Aminobiphenyl palladacycles are among the most successful precatalysts for Pd-catalyzed cross-coupling reactions, including aryl amination. However, the role of NH-carbazole, a byproduct of precatalyst activation, remains poorly understood. Herein, the mechanism of the aryl amination reactions catalyzed by a cationic 2-aminobiphenyl palladacycle supported by a terphenyl phosphine ligand, PCyp 2 Ar Xyl2 (Cyp = cyclopentyl; Ar Xyl2 = 2,6bis(2,6-dimethylphenyl)phenyl), P1, has been thoroughly investigated. Combining computational and experimental studies, we found that the Pd(II) oxidative addition intermediate reacts with NH-carbazole in the presence of the base (NaO t Bu) to yield a stable aryl carbazolyl Pd(II) complex. This species functions as the catalyst resting state, providing the amount of monoligated LPd(0) species required for catalysis and minimizing Pd decomposition. In the case of a reaction with aniline, an equilibrium between the carbazolyl complex and the on-cycle anilido analogue is established, which allows for a fast reaction at room temperature. In contrast, heating is required in a reaction with alkylamines, whose deprotonation involves coordination to the Pd center. A microkinetic model was built combining computational and experimental data to validate the mechanistic proposals. In conclusion, our study shows that despite the rate reduction observed in some reactions by the formation of the aryl carbazolyl Pd(II) complex, this species reduces catalyst decomposition and could be considered an alternative precatalyst in cross-coupling reactions.

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“…Recently, we reported on the synthesis of a family of dialkylterphenyl phosphines and discussed their steric and electronic properties . These phosphines can adopt different coordination modes involving the P atom and one of the flanking aryl rings of the terphenyl fragment. , We showed that 2-aminobiphenyl palladacycles ligated with the bulkier ligand PCyp 2 Ar Xyl2 (Cyp = cyclopentyl; Ar Xyl2 = 2,6-bis(2,6-dimethylphenyl)phenyl) are excellent precatalysts for the Buchwald–Hartwig reaction of deactivated aryl chlorides with a variety of N -nucleophiles . To expand the array of electrophiles that can be applied in this transformation, we focused on challenging aryl sulfamates, since, to our knowledge, they have not been used as coupling partners in palladium-catalyzed Buchwald–Hartwig aminations. , Furthermore, the substrate scope of Ni catalysts reported for the amination of aryl sulfamates remains limited to anilines and secondary alkyl amines (Figure A).…”

Section: Introductionmentioning

confidence: 99%

Broad-Scope Amination of Aryl Sulfamates Catalyzed by a Palladium Phosphine Complex

et al. 2023

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Among phenol-derived electrophiles, aryl sulfamates are attractive substrates since they can be employed as directing groups for C−H functionalization prior to catalysis. However, their use in C−N coupling is limited only to Ni catalysis. Here, we describe a Pd-based catalyst with a broad scope for the amination of aryl sulfamates. We show that the N-methyl-2-aminobiphenyl palladacycle supported by the PCyp 2 Ar Xyl2 ligand (Cyp = cyclopentyl; Ar Xyl2 = 2,6-bis(2,6dimethylphenyl)phenyl) efficiently catalyzes the C−N coupling of aryl sulfamates with a variety of nitrogen nucleophiles, including anilines, primary and secondary alkyl amines, heteroaryl amines, N-heterocycles, and primary amides. DFT calculations support that the oxidative addition of the aryl sulfamate is the rate-determining step. The C−N coupling takes place through a cationic pathway in the polar protic medium.

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N-substituted aminobiphenyl palladacycles stabilized by dialkylterphenyl phosphanes: Preparation and applications in C N cross-coupling reactions

Cited by 7 publications

References 53 publications

Recent Progress Concerning the N-Arylation of Indoles

Recent Progress Concerning the N-Arylation of Indoles

Important Role of NH-Carbazole in Aryl Amination Reactions Catalyzed by 2-Aminobiphenyl Palladacycles

Broad-Scope Amination of Aryl Sulfamates Catalyzed by a Palladium Phosphine Complex

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