Nickel-Catalyzed Negishi Cross-Coupling Research Articles

Nickel-Catalyzed Negishi Cross-Coupling of Alkyl Halides, Including Unactivated Tertiary Halides, with a Boron-Stabilized Organozinc Reagent.

Nickel-catalyzed cross-coupling of unactivated tertiary alkyl electrophiles with alkylmetal reagents is still a challenge. We report herein a nickel-catalyzed Negishi cross-coupling of alkyl halides, including unactivated tertiary halides, with boron-stabilized organozinc reagent BpinCH2ZnI, yielding versatile organoboron products with high functional-group tolerance. Importantly, the Bpin group was found to be indispensable for accessing the quaternary carbon center. The synthetic practicability of the prepared quaternary organoboronates was demonstrated by their conversion to other useful compounds.

Visible-Light-Induced Nickel-Catalyzed Negishi Cross-Couplings by Exogenous-Photosensitizer-Free Photocatalysis.

The merging of photoredox and transition-metal catalysis has become one of the most attractive approaches for carbon-carbon bond formation. Such reactions require the use of two organo-transition-metal species, one of which acts as a photosensitizer and the other one as a cross-coupling catalyst. We report herein an exogenous-photosensitizer-free photocatalytic process for the formation of carbon-carbon bonds by direct acceleration of the well-known nickel-catalyzed Negishi cross-coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross-coupling chemistry that involve the direct visible-light absorption of organometallic catalytic complexes.

Nickel-Catalyzed Negishi Cross-Coupling of N-Acylsuccinimides: Stable, Amide-Based, Twist-Controlled Acyl-Transfer Reagents via N–C Activation

This paper reports a room temperature, nickel-catalyzed Negishi cross-coupling of N-acylsuccinimides with arylzinc reagents via selective N–C bond cleavage enabled by amide bond twist. The reaction proceeds using a commercially available, air-stable Ni(II) precatalyst in the absence of additives under exceedingly mild conditions. Of broad interest, this report introduces N-acylsuccinimides as stable, crystalline, electrophilic, cost-effective, benign, amide-based acyl transfer reagents via acyl metal intermediates. The reaction selectivity is governed by half-twist of the amide bond in N-acylsuccinimides, thus opening the door for applications in metal-catalyzed manifolds via redox­-neutral reaction pathways tuneable by amide bond distortion.

Nickel-Catalyzed Negishi Cross-Coupling with Styrenyl Aziridines

Nickel-Catalyzed Negishi Cross-Coupling with Styrenyl Aziridines

Directed Nickel-Catalyzed Negishi Cross Coupling of Alkyl Aziridines

Herein we report a nickel-catalyzed C-C bond-forming reaction between simple alkyl aziridines and organozinc reagents. This method represents the first catalytic cross-coupling reaction employing a nonallylic and nonbenzylic Csp(3)-N bond as an electrophile. Key to its success is the use of a new N-protecting group (cinsyl or Cn) bearing an electron-deficient olefin that directs oxidative addition and facilitates reductive elimination. Studies pertinent to elucidation of the mechanism of cross coupling are also presented.

4-Organochalcogenoyl-1H-1,2,3-triazoles: synthesis and functionalization by a nickel-catalyzed Negishi cross-coupling reaction

A general method for the synthesis of triazoles containing selenium and tellurium was accomplished via a CuCAAC reaction between organic azides and a terminal triple bond, generated by in situ deprotection of the silyl group. The reaction tolerates alkyl and arylazides, with alkyl and aryl substituents directly bonded to the chalcogen atom. The products were readily functionalized by a nickel-catalyzed Negishi cross-coupling reaction, furnishing the aryl-heteroaryl products at the 4-position in good yields.

Regioselective Synthesis of Trialkylpyrazines via Nickel-Catalyzed Negishi Cross-Coupling of Pyrazine Triflate

A regioselective synthesis of trialkylpyrazines via nickel-catalyzed cross-coupling reaction of pyrazine triflate is reported. The 5-substituted 2,3-dimethylpyrazine derivatives including trail pheromone components of the ant <i>Eutetramorium mocquerysi</i> have been successfully synthesized in good yields by nickel-catalyzed Negishi cross-coupling reactions of pyrazine triflate mediated by alkyl and arylzinc halides.

Nickel-Catalyzed Negishi Cross-Coupling Reactions of Secondary Alkylzinc Halides with 6-Chloropurines

An efficient method for the synthesis of 6-acyclic secondary alkyl purines was developed via nickel-catalyzed Negishi cross-cupling of 6-chloropurines with acyclic secondary alkylzinc halides in the presence of phenanthroline at room temperature. The process gave good to excellent isolated yields under very mild conditions.

Nickel-Catalyzed Negishi Cross-Coupling Reactions of Secondary Alkylzinc Halides and Aryl Iodides

A general Ni-catalyzed process for the cross-coupling of secondary alkylzinc halides and aryl/heteroaryl iodides has been developed. This is the first process to overcome the isomerization and β-hydride elimination problems that are associated with the use of secondary nucleophiles, and that have limited the analogous Pd-catalyzed systems. The impact of salt additives was also investigated. It was found that the presence of LiBF(4) dramatically improves both isomeric retention and yield for challenging substrates.

Nickel-catalyzed Negishi cross-couplings of 6-chloropurines with organozinc halides at room temperature

An efficient method for the synthesis of 6-alkyl or 6-aryl purines (nucleosides) was developed via nickel-catalyzed Negishi cross-couplings of 6-chloropurines and organozinc halides. The ligand-free process gave good to excellent isolated yields at room temperature.

Efficient Cross-Coupling of Aryl Chlorides with Arylzinc Reagents Catalyzed by Amido Pincer Complexes of Nickel

The nickel-catalyzed Negishi cross-coupling reaction of aryl chlorides with arylzinc compounds was investigated. The nickel complexes with the amido pincer type of ligands exhibited high catalytic activity and good functional group tolerance.

Asymmetric Nickel-Catalyzed Negishi Cross-Couplings of Secondary α-Bromo Amides with Organozinc Reagents

A Ni/Pybox catalyst achieves the asymmetric cross-coupling of secondary alpha-bromo amides with organozinc reagents. The process tolerates a variety of functional groups and affords the desired product in good yield and in high enantiomeric excess.