Nickel-catalyzed Hydrocyanation Research Articles

Photochemical Synthesis of Nitriles from Alcohols.

Nickel-catalyzed hydrocyanation of 1,3-butadiene with hydrogen cyanide gas is the predominant method for the synthesis of adiponitrile, which is an important precursor for polymer production. However, the use of fossil-derived alkenes raises environmental concerns, and hydrogen cyanide is highly volatile and extremely toxic. Herein, we report the use of biomass-derived 1,4-butanediol, as well as other primary alcohols, for photochemical synthesis of linear and branched nitriles and dinitriles, including adiponitrile, with 1,4-dicyanobenzene as the CN source. This mild, sustainable method does not require hydrogen cyanide gas or an air- or moisture-sensitive metal catalyst and is applicable for the production of dinitriles as precursors of diamines, which have potential utility for the development of novel polyamides.

Nickel(BiPhePhos)-Catalyzed Hydrocyanation of Styrene—Highly Increased Catalytic Activity by Optimized Operational Procedures

Nitriles are versatile and highly desired chemical intermediates for a range of products. Their economic large-scale production requires highly efficient and selective synthesis. The nickel-catalyzed hydrocyanation of C=C double bonds provides such selective and 100% atom-economical access to nitriles, but the catalysts hitherto lack activity and longevity. Yet, the literature focusing on increased catalytic activity or optimized operational procedures is scarce, at the least. Here, we present a thorough investigation and optimization of operational procedures using a commercially available diphosphite ligand and styrene as a model substrate. This led us to achieve a TOF20 of more than 300,000 h−1.

Nickel-Catalyzed Hydrocyanation of Alkynes Using a Malononitrile as Transnitrilation Reagent

Nickel-Catalyzed Hydrocyanation of Alkynes Using a Malononitrile as Transnitrilation Reagent

Ligand-Controlled Regiodivergent Nickel-Catalyzed Hydrocyanation of Silyl-Substituted 1,3-Diynes.

A regiodivergent nickel-catalyzed hydrocyanation of 1-aryl-4-silyl-1,3-diynes is reported. When appropriate bisphosphine and phosphine-phosphite ligands are applied, the same starting materials can be converted into two different enynyl nitriles with good yields and high regioselectivities. The DFT calculations unveiled that the structural features of different ligands bring divergent alkyne insertion modes, which in turn lead to different regioselectivities. Moreover, the synthetic value of the cyano-containing 1,3-enynes has been demonstrated with several downstream transformations.

Regio-, Chemo-, and Enantioselective Ni-Catalyzed Hydrocyanation of 1,3-Dienes.

A regio-, chemo-, and enantioselective nickel-catalyzed hydrocyanation of 1,3-dienes is reported. The key to the success of this asymmetric transformation is the use of a specific multichiral diphosphite ligand. In addition to aryl-substituted 1,3-dienes, highly challenging aliphatic 1,3-diene substrates can also be preferentially converted to the corresponding 1,2-adducts in decent yields with the highest enantioselectivities to date.

Nickel-catalyzed highly regioselective hydrocyanation of aliphatic allenes

A nickel-catalyzed hydrocyanation of aliphatic allenes with excellent regioselectivity is developed. This protocol enables a catalytic pathway to access various allylic nitriles containing quaternary carbon centers in good yields.

Nickel‐Catalyzed Migratory Hydrocyanation of Internal Alkenes: Unexpected Diastereomeric‐Ligand‐Controlled Regiodivergence

A regiodivergent nickel-catalyzed hydrocyanation of a broad range of internal alkenes involving a chain-walking process is reported. When appropriate diastereomeric biaryl diphosphite ligands are applied, the same starting materials can be converted to either linear or branched nitriles with good yields and high regioselectivities. DFT calculations suggested that the catalyst architecture determines the regioselectivity by modulating electronic and steric interactions. In addition, moderate enantioselectivities were observed when branched nitriles were produced.

Highly Enantioselective Nickel-Catalyzed Hydrocyanation of Disubstituted Methylenecyclopropanes Enabled by TADDOL-based Diphosphite Ligands.

A vast range of novel TADDOL-based diphosphite ligands were first synthesized and applied in the nickel-catalyzed asymmetric hydrocyanation of disubstituted methylenecyclopropanes. By employing these new catalysts, the conversion of diverse methylenecyclopropanes into their corresponding allylic nitriles was first enabled, in good yield with excellent enantioselectivities.

Mechanistic Study of Unprecedented Highly Regioselective Hydrocyanation of Terminal Alkynes: Insight into the Origins of the Regioselectivity and Ligand Effects.

Density functional theory (DFT) calculations were performed to gain insight into the mechanism of the nickel-catalyzed hydrocyanation of terminal alkynes with Zn(CN)2 and water to exclusively generate the branched nitrile with excellent Markovnikov selectivity. After precatalyst activation to give the LNi(0) active species, the transformation proceeds via the following steps: (1) oxidative addition of H2 O to the LNi(0) provides the intermediate LNi(II)H(OH); (2) ligand exchange of LNi(II)H(OH) with Zn(CN)2 gives the intermediate LNi(II)H(CN); (3) alkyne insertion to the LNi(II)H(CN) forms the alkenyl nickel complex, followed by the reductive elimination step reaching the final product. This mechanism is kinetically and thermodynamically more favorable than that of the experimental proposed ones. On the basis of the experimental observations, more water molecules cannot further improve the reaction as it has also been rationalized. Furthermore, the origin of the high regioselectivity of the product, the variable effectiveness of the metal mediator as function of ligands, as well as the high yield of the alkyl-substituted alkynes substrates, is analyzed in detail. © 2019 Wiley Periodicals, Inc.

Nickel-Catalyzed Hydrocyanation of Allenes and Its Application.

Cyano (CN) groups are equivalent to carbonyl as well as amino- and hydroxymethyl groups. Therefore, their catalytic introduction under metal catalysis is an important issue in synthetic organic chemistry. Ni-catalyzed hydrocyanation is one of the most well-investigated, powerful tools for installing a CN group. However, it is still difficult to control chemo- and regioselectivity. In this review, the author uses allenes to enable regio-, stereo-, and face-selective transformations to natural product synthesis and axial chirality transfer.

Nickel-catalyzed Hydrocyanation of Carbon-Carbon Multiple Bonds and its Application

Nickel-catalyzed Hydrocyanation of Carbon-Carbon Multiple Bonds and its Application

Nickel-catalyzed highly regioselective hydrocyanation of alkenes with Zn(CN)2

The first general and regioselective nickel-catalyzed hydrocyanation of terminal alkenes with Zn(CN)2 using an air-stable and inexpensive nickel(ii) salt as the precatalyst has been developed.

Nickel-Catalyzed Highly Regioselective Hydrocyanation of Terminal Alkynes with Zn(CN)2 Using Water as the Hydrogen Source.

The first efficient and general nickel-catalyzed hydrocyanation of terminal alkynes with Zn(CN)2 in the presence of water has been developed. The reaction provides a regioselective protocol for the synthesis of functionalized vinyl nitriles with a range of structural diversity under mild reaction conditions while obviating use of the volatile and hazardous reagent of HCN. Deuterium-labeling experiments confirmed the role of water as the hydrogen source in this hydrocyanation reaction.

Transfer of axial chirality through the nickel-catalysed hydrocyanation of chiral allenes.

The transfer of axial chirality of allenes is beginning to be exploited as a powerful method for creating central chirality, particularly through the use of transition metal catalysis. In this communication, the transfer of axial chirality of chiral allenes via nickel-catalysed hydrocyanation is achieved through both regio- and face-selective hydronickelation as well as regioselective reductive elimination. This protocol was applied to 12 substrates and gave chiral carbonitriles with up to 97% ee. Further application to hydrocyanative cyclization using a chiral allene-yne is also presented, along with a discussion of the corresponding mechanism of racemization.

Efficient nickel-catalyzed hydrocyanation of alkenes using acetone cyanohydrin as a safer cyano source

An active nickel catalyst prepared in situ from a Ni(II) compound, phosphine ligand, and zinc powder was found to be an efficient catalyst system for the hydrocyanation of various alkenes using acetone cyanohydrin as a safer cyano source. The combination of NiCl2·6H2O and 1,3-bis(diphenylphosphino)propane was the most efficient catalyst precursor in DMF. Under the optimized conditions, various styrenes, heterocyclic alkenes, and aliphatic alkenes were converted to their corresponding nitriles in excellent yields.

ChemInform Abstract: Application of Chelating Diphosphine Ligands in the Nickel-Catalyzed Hydrocyanation of Alk-1-enes and ω-Unsaturated Fatty Acid Esters.

ChemInform Abstract: Application of Chelating Diphosphine Ligands in the Nickel-Catalyzed Hydrocyanation of Alk-1-enes and ω-Unsaturated Fatty Acid Esters.

ChemInform Abstract: Asymmetric Hydrocyanation of Olefins Catalyzed by Chiral Diphosphite-Nickel Complexes.

Abstract Chiral aryl diphosphite ligands derived from binaphthol were found to be effective in the nickel-catalyzed hydrocyanation of a variety of olefins. Enantioselective hydrocyanations of styrene, 4-substituted styrenes and norbornene were achieved with excellent regioselectivity and moderate enantioselectivity. The hydrocyanation of vinyl acetate gave 72.9% ee. The catalytic activity and the enantioselectivity of the Ni(0)–diphosphite complexes were found to be highly dependent on the structures of the ligands.

Ligand development in the Ni-catalyzed hydrocyanation of alkenes

The addition of HCN to alkenes is a very useful reaction for the synthesis of functional organic substrates. Industrially the nickel-catalyzed hydrocyanation has gained considerable importance mainly because of the production of adiponitrile in the DuPont process. In this process the hydrocyanation of butadiene is carried out using aryl phosphite-modified nickel catalyst. Since the performance of organo-transition metal complexes is largely determined by the ligand environment of the metal, fundamental understanding and ligand development is of pivotal importance for any progress. This feature article gives an account of the development and application of different mono- and bidentate phosphorus-based ligands in the Ni-catalyzed hydrocyanation reaction of alkenes. Special attention will be paid to the development of insight and understanding of the ligand structural and electronic properties towards the improvement of the catalyst performance in terms of stability, activity, and selectivity.

Novel Chelating Phosphonite Ligands: Syntheses, Structures, and Nickel-Catalyzed Hydrocyanation of Olefins

A series of sterically tuned chelating bisarylphosphonite ligands with a cis-1,2-(bi)cycloalkane spacer and cyclic phosphonite moieties was synthesized. The spacer as well as the phosphacycles were modified to investigate their influence in the nickel-catalyzed hydrocyanation of styrene and 1,3-butadiene and the isomerization of 2-methyl-3-butenenitrile. NMR studies detect only catalytically active (P∩P)Ni(COD) species and no hints of the formation of catalytically inactive dibisphosphonite complexes (P∩P)2Ni are found. In the hydrocyanation of styrene, these catalysts are highly active (93% conversion) and highly regioselective (99.9% iso) at moderate catalyst concentrations (1 mol %). They also proved to be very active in the hydrocyanation of butadiene with turnover numbers of 644 and turnover frequencies of 426 h−1 at low catalyst concentrations (0.1 mol %). Moreover, they very efficiently catalyze the isomerization of 2-methyl-3-butenenitrile to the linear 3-pentenenitrile.

The Enantioselective Step in the Nickel-Catalyzed Hydrocyanation of 1,3-Cyclohexadiene

On the basis of deuterium labeling experiments and an equal 1,2-/1,4-product distribution, the reductive elimination of the product has been established to be the enantioselective step in the nickel-catalyzed hydrocyanation of 1,3-cyclohexadiene. This could be achieved by successfully exploiting the rather unique features of this reaction: identical product formation for 1,2- and 1,4-addition, cis addition over the diene, and high enantiomeric excess.