Nickel-Catalyzed Suzuki-Miyaura Coupling Research Articles

ProPhos: A Ligand for Promoting Nickel-Catalyzed Suzuki-Miyaura Coupling Inspired by Mechanistic Insights into Transmetalation.

Nickel-catalyzed Suzuki-Miyaura coupling (Ni-SMC) offers the potential to reduce the cost of pharmaceutical process synthesis. However, its application has been restricted by challenges such as slow reaction rates, high catalyst loading, and a limited scope of heterocycles. Despite recent investigations, the mechanism of transmetalation in Ni-SMC, often viewed as the turnover-limiting step, remains insufficiently understood. We elucidate the "Ni-oxo" transmetalation pathway, applying PPh2Me as the ligand, and identify the formation of a nickel-oxo intermediate as the turnover-limiting step. Building on this insight, we develop a scaffolding ligand, ProPhos, featuring a pendant hydroxyl group connected to the phosphine via a linker. The design preorganizes both the nucleophile and the nickel catalyst, thereby facilitating transmetalation. This catalyst exhibits fast kinetics and robust activity across a wide range of heteroarenes, with a catalyst loading of 0.5-3 mol %. For arene substrates, the catalyst loading can be further reduced to 0.1 mol %.

Nickel-Catalyzed Suzuki-Miyaura Coupling in Water for the Synthesis of 2-Aryl Allyl Phosphonates and Sulfones.

An operationally simple and green protocol using a NiSO4·6H2O/cationic 2,2'-bipyridyl ligand system as a water-soluble catalyst for the coupling of arylboronic acids with (2-haloallyl)phosphonates and (2-haloallyl)sulfones in water under air was developed. The reaction was performed at 120 °C with arylboronic acids (2 mmol) and (2-haloallyl)phosphonates or sulfones (1 mmol) in the presence of 5 mol % of the Ni catalytic system in a basic aqueous solution for 1 h, giving the corresponding 2-aryl allyl phosphonates or sulfones in good to excellent yields. This reaction features the use of an abundant transition metal as a catalyst in water and exhibits high functional group tolerance, rendering it an eco-friendly procedure.

Density Functional Theory Mechanistic Insight into the Base-Free Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling of Acid Fluoride: Concerted versus Stepwise Transmetalation.

Density functional theory mechanistic study has been carried out to account for the base-free nickel-catalyzed Suzuki-Miyaura coupling of acid fluorides (ArC(O)F) with boronic acids (Ar'B(OH)2). After oxidative addition to break the C-F bond of acid fluoride, the resultant ArC(O)[Ni]F species undergoes transmetalation with Ar'B(OH)2 to give ArC(O)[Ni]Ar'. Subsequently, ArC(O)[Ni]Ar' can either undergo decarbonylation, finally leading to the coupling product (ArAr'), or reductive elimination to give ketone byproduct ArC(O)Ar'. The kinetic competition between the two pathways controls the chemoselectivity of the reaction, and transmetalation is the rate-determining step of the coupling. Importantly, it was found that transmetalation prefers a stepwise mechanism over a conventional concerted one. Detailed analyses indicate that the strong fluorophilicity of boron facilitates the base-free transmetalation and the coordination interaction between an oxygen atom of boronic acid and nickel gears the base-free transmetalation to undergo the stepwise pathway. The stepwise transmetalation mechanism also involves the nickel-catalyzed Suzuki-Miyaura coupling of aldehydes with ketone (PhC(O)CF3) as the transmetalation promoter.

Chemoenzymatic conversion of amides to enantioenriched alcohols in aqueous medium

One-pot reactions that combine non-enzymatic and biocatalytic transformations represent an emerging strategy in chemical synthesis. Some of the most powerful chemoenzymatic methodologies, although uncommon, are those that form a carbon–carbon (C–C) bond and a stereocenter at one of the reacting carbons, thereby streamlining traditional retrosynthetic disconnections. Here we report the one-pot, chemoenzymatic conversion of amides to enantioenriched alcohols. This transformation combines a nickel-catalyzed Suzuki–Miyaura coupling of amides in aqueous medium with an asymmetric, biocatalytic reduction to provide diarylmethanol derivatives in high yields and enantiomeric excesses. The synthetic utility of this platform is underscored by the formal syntheses of both antipodes of the pharmaceutical orphenadrine, which rely on ketoreductase enzymes that instill complementary stereoselectivities. We provide an explanation for the origins of stereoselectivity based on an analysis of the enzyme binding pockets.

Taming Nickel-Catalyzed Suzuki-Miyaura Coupling: A Mechanistic Focus on Boron-to-Nickel Transmetalation

The mechanism of boron-to-nickel transmetalation, the key step of the nickel-catalyzed Suzuki-Miyaura (S-M) coupling, was examined both experimentally and theoretically. Dinuclear μ-hydroxo-bridged complexes formed by reaction of trans-[ArNi(PR3)2X] with hydroxide are not directly involved in transmetalation, but they rather act as a resting state for the catalyst. The base/boronic acid ratio is the crucial parameter, as it modulates the extent of formation of these dinuclear species and thus tunes the catalytic activity. These findings explain some limitations encountered in practical applications of nickel-catalyzed S-M couplings and suggest how to tailor the experimental conditions in order to overcome these difficulties.

Nickel-Catalyzed Suzuki-Miyaura Coupling of Aliphatic Amides.

We report the Ni-catalyzed Suzuki-Miyaura coupling of aliphatic amide derivatives. Prior studies have shown that aliphatic amide derivatives can undergo Ni-catalyzed carbon-heteroatom bond formation but that Ni-mediated C-C bond formation using aliphatic amide derivatives has remained difficult. The coupling disclosed herein is tolerant of considerable variation with respect to both the amide-based substrate and the boronate coupling partner and proceeds in the presence of heterocycles and epimerizable stereocenters. Moreover, a gram-scale Suzuki-Miyaura coupling/Fischer indolization sequence demonstrates the ease with which unique polyheterocyclic scaffolds can be constructed, particularly by taking advantage of the enolizable ketone functionality present in the cross-coupled product. The methodology provides an efficient means to form C-C bonds from aliphatic amide derivatives using nonprecious-metal catalysis and offers a general platform for the heteroarylation of aliphatic acyl electrophiles.

Nickel-Catalyzed Suzuki–Miyaura Coupling of CF3O-Containing Benzyl Bromides

Nickel-Catalyzed Suzuki–Miyaura Coupling of CF3O-Containing Benzyl Bromides

Enantioselective Construction of Trifluoromethoxylated Stereogenic Centers by a Nickel‐Catalyzed Asymmetric Suzuki–Miyaura Coupling of Secondary Benzyl Bromides

Trifluoromethoxy-substituted stereogenic centers can be constructed with high enantioselectivity by a nickel-catalyzed Suzuki-Miyaura coupling of readily available α-bromobenzyl trifluoromethyl ethers with a variety of aryl pinacol boronates. The coupling proceeds under mild reaction conditions, and a variety of common functional groups, such as fluoride, chloride, bromide, ester, enolizable ketone, nitro, cyano, amino, and vinyl moieties, were well tolerated. Furthermore, the reaction can be easily scaled up to gram quantities without a decrease in enantioselectivity.

Synthesis of Biaryls through Nickel-Catalyzed Suzuki-Miyaura Coupling of Amides by Carbon-Nitrogen Bond Cleavage.

The first Ni-catalyzed Suzuki-Miyaura coupling of amides for the synthesis of widely occurring biaryl compounds through N-C amide bond activation is reported. The reaction tolerates a wide range of electron-withdrawing, electron-neutral, and electron-donating substituents on both coupling partners. The reaction constitutes the first example of the Ni-catalyzed generation of aryl electrophiles from bench-stable amides with potential applications for a broad range of organometallic reactions.

Nickel-Catalyzed Suzuki-Miyaura Coupling in t-Amyl Alcohol for the Preparation of 5-(Furan-3-yl)pyrimidine

Nickel-Catalyzed Suzuki-Miyaura Coupling in t-Amyl Alcohol for the Preparation of 5-(Furan-3-yl)pyrimidine

ChemInform Abstract: Nickel‐Catalyzed Suzuki—Miyaura Coupling of a Tertiary Iodocyclopropane with Wide Boronic Acid Substrate Scope: Coupling Reaction Outcome Depends on Radical Species Stability.

AbstractThis is the first transition metal‐catalyzed Suzuki—Miyaura coupling reaction between a tertiary alkyl halide and a wide variety of aromatic boronic acids.

ChemInform Abstract: Nickel‐Catalyzed One‐Pot Synthesis of Biaryls from Phenols and Arylboronic Acids via C—O Activation Using TCT Reagent.

Abstract In this study, the direct Nickel-catalyzed Suzuki–Miyaura coupling reaction of phenols and arylboronic acids via C–O bond activation using 2,4,6-trichloro-1,3,5-triazine (TCT) is described. Initially, phenols were reacted with TCT to give the corresponding 2,4,6-triaryloxy-1,3,5-triazine (TAT) products. Subsequently, arylboronic acid, base and Ni-catalyst were added to the generated aryl C–O electrophile to obtain the final biaryl product. This study represents a simple and direct method for the synthesis of biaryls from phenolic compounds using sub-stoichiometric amounts of TCT as a cheap and readily available C–O activating reagent.

Selective synthesis of either enantiomer of an anti-breast cancer agent via a common enantioenriched intermediate

A stereoselective synthesis of a bioactive triarylmethane is described. Key to the synthesis is a nickel-catalyzed Suzuki–Miyaura coupling which proceeds with retention at the benzylic center. This method is complementary to our previously reported nickel-catalyzed Kumada coupling which proceeds with inversion. Together, the two methods allow for efficient access to either enantiomer of biologically relevant triarylmethanes from a common enantioenriched intermediate.

Nickel-catalyzed one-pot synthesis of biaryls from phenols and arylboronic acids via C–O activation using TCT reagent

In this study, the direct Nickel-catalyzed Suzuki–Miyaura coupling reaction of phenols and arylboronic acids via C–O bond activation using 2,4,6-trichloro-1,3,5-triazine (TCT) is described. Initially, phenols were reacted with TCT to give the corresponding 2,4,6-triaryloxy-1,3,5-triazine (TAT) products. Subsequently, arylboronic acid, base and Ni-catalyst were added to the generated aryl C–O electrophile to obtain the final biaryl product. This study represents a simple and direct method for the synthesis of biaryls from phenolic compounds using sub-stoichiometric amounts of TCT as a cheap and readily available C–O activating reagent.

Nickel-catalyzed Suzuki-Miyaura couplings in green solvents.

The nickel-catalyzed Suzuki-Miyaura coupling of aryl halides and phenol-derived substrates with aryl boronic acids using green solvents, such as 2-Me-THF and tert-amyl alcohol, is reported. This methodology employs the commercially available and air-stable precatalyst, NiCl2(PCy3)2, and gives biaryl products in synthetically useful to excellent yields. Using this protocol, bis(heterocyclic) frameworks can be assembled efficiently.

Nickel-Catalyzed Suzuki–Miyaura Coupling of Heteroaryl Ethers with Arylboronic Acids

Nickel-catalyzed Suzuki-Miyaura coupling of heteroaryl ethers with arylboronic acids was described. Selective activation of the phenol C-O bonds was achieved by converting them into the corresponding aryl 2,4-dimethoxy-1,3,5-triazine-6-yl ethers, in which aryl C-O bond could be selectively cleaved with inexpensive, air-stable NiCl2(dppf) as a catalyst. Coupling of these readily accessible heteroaryl ethers proved tolerant of extensive functional groups.

Nickel-Catalyzed Suzuki-Miyaura Coupling of Aryl Carbamates, Carbonates, and Sulfamates

Efficient Suzuki-Miyaura cross-coupling of aryl carbamates, carbonates, and sul­famates was implemented. The reaction proceeds with moderate to good yields at elevated temperatures using an air-stable nickel(II) catalyst.