Synthesis of Aromatic Nitriles Using Nonmetallic Cyano-Group Sources

Non-toxic cyanide sources and cyanating agents

The present review gives an overview over non-toxic cyanation agents and cyanide sources used in the synthesis of structurally diverse products containing the nitrile function. Nucleophilic as well as electrophilic agents/systems that transfer the entire CN-group were taken in consideration. Reactions in which a preexisting carbon functionality is transformed into a nitrile function by addition of nitrogen are however not covered here.

Rhodium(iii)-catalyzed aromatic C–H cyanation with dimethylmalononitrile as a cyanating agent

Safe, bench-stable, and commercially available DMMN was used as a cyanating reagent in Rh(iii)-catalyzed aromatic C–H bond direct cyanation in the presence of copper oxide as a promotor.

Oxidant free conversion of alcohols to nitriles over Ni-based catalysts

Ni-Based catalysts converting various primary alcohols to nitriles in high yields under oxidant-free, low temperature conditions.

Copper-catalysed C(sp3)–N coupling initiated by selective C–C bond cleavage of cyclobutanone oxime esters

A mild and practical protocol is developed for the synthesis of functionalized 4-(arylamino)butanenitriles via selective C–C bond cleavage and subsequent C(sp³)–N coupling.

Double metal cyanides as heterogeneous Lewis acid catalysts for nitrile synthesis via acid-nitrile exchange reactions

A series of transition metal-based double metal cyanides (DMCs) were studied as catalysts for the synthesis of nitriles via acid-nitrile exchange reaction.

Cyanofluorination of vinyl ethers enabled by electron donor–acceptor complexes

The reaction is operationally simple and conducted under ambient conditions, allowing the access to highly functionalized α-alkoxy-β-fluoronitriles bearing quaternary carbons that are difficult to access by existing methods.

Nickel-catalyzed cyanation of aryl halides and triflates using acetonitrile via C-CN bond cleavage assisted by 1,4-bis(trimethylsilyl)-2,3,5,6-tetramethyl-1,4-dihydropyrazine

A catalyst system of [Ni(MeCN)₆](BF₄)₂, 1,10-phenanthroline, and 1,4-bis(trimethylsilyl)-2,3,5,6-tetramethyl-1,4-dihydropyrazine (Si–Me₄-DHP) assisted cyanation of aryl halides in acetonitrile to give the corresponding aryl nitriles.

We developed a non-toxic cyanation reaction of various aryl halides and triflates in acetonitrile using a catalyst system of [Ni(MeCN)₆](BF₄)₂, 1,10-phenanthroline, and 1,4-bis(trimethylsilyl)-2,3,5,6-tetramethyl-1,4-dihydropyrazine (Si–Me₄-DHP). Si–Me₄-DHP was found to function as a reductant for generating nickel(0) species and a silylation reagent to achieve the catalytic cyanation via C–CN bond cleavage.

Catalytic Promiscuity of Galactose Oxidase: A Mild Synthesis of Nitriles from Alcohols, Air, and Ammonia

We report an unprecedented catalytically promiscuous activity of the copper-dependent enzyme galactose oxidase. The enzyme catalyses the one-pot conversion of alcohols into the related nitriles under mild reaction conditions in ammonium buffer, consuming ammonia as the source of nitrogen and dioxygen (from air at atmospheric pressure) as the only oxidant. Thus, this green method does not require either cyanide salts, toxic metals, or undesired oxidants in stoichiometric amounts. The substrate scope of the reaction includes benzyl and cinnamyl alcohols as well as 4- and 3-pyridylmethanol, giving access to valuable chemical compounds. The oxidation proceeds through oxidation from alcohol to aldehyde, in situ imine formation, and final direct oxidation to nitrile.

Metal-Free Direct C-H Cyanation of Alkenes

A metal‐free and direct alkene C−H cyanation is described. Directing groups are not required and the mechanism involves electrophilic activation of the alkene by a cyano iodine(III) species generated in situ from a [bis(trifluoroacetoxy)iodo]arene and trimethylsilyl cyanide as the cyanide source. This C−H functionalization can be conducted on gram scale, and for noncyclic 1,1‐ and 1,2‐disubstuted alkenes high stereoselectivity is achieved, thus rendering the method highly valuable.

Selective Synthesis of Aryl Nitriles and 3-Imino-1-oxoisoindolines via Nickel-Promoted C(sp2)-H Cyanations

An efficient nickel-promoted selective monocyanation of benzamides with TMSCN via 8-aminoquinoline directed ortho C-H activation has been developed. Varieties of functionalized ortho-cyanated (hetero)aryl nitriles can be selectively synthesized in moderate to good yields. These cyanation products can be easily transformed into various 3-imino-1-oxoisoindolines in a one-pot procedure. The mild reaction conditions, use of cheap and commercially available reagents, wide functional group tolerance, and operational convenience make this protocol practical to the synthetic community.

Palladium and Lewis-Acid-Catalyzed Intramolecular Aminocyanation of Alkenes: Scope, Mechanism, and Stereoselective Alkene Difunctionalizations

An expansion of methodologies aimed at the formation of versatile organonitriles, via the intramolecular aminocyanation of unactivated alkenes, is herein reported. Importantly, the need for a rigid tether in these reactions has been obviated. The ease-of-synthesis and viability of substrates bearing flexible backbones has permitted for diastereoselective variants as well. We demonstrated the utility of this methodology with the formation of pyrrolidones, piperidinones, isoindolinones, and sultams. Furthermore, subsequent transformation of these motifs into medicinally relevant molecules is also demonstrated. A double crossover ¹³C-labeling experiment is consistent with a fully intramolecular cyclization mechanism. Deuterium labeling experiments support a mechanism involving syn-addition across the alkene.

Pd-Catalyzed one-pot dehydroxylative coupling of phenols with K4[Fe(CN)6] mediated by SO2F2: a practical method for the direct conversion of phenols to aryl nitriles

A SO₂F₂ mediated Pd-catalyzed one-pot dehydroxylative cyanation of phenols to aryl nitriles was accomplished by employing (K₄[Fe(CN)₆]) as the cyanating reagent.

Nickel-catalyzed cyanation of phenol derivatives activated by 2,4,6-trichloro-1,3,5-triazine

A nickel-catalyzed cyanation of phenol derivatives activated by 2,4,6-trichloro-1,3,5-triazine (TCT) using aminoacetonitrile as the cyanating agent is described.

A mineralogically-inspired silver–bismuth hybrid material: an efficient heterogeneous catalyst for the direct synthesis of nitriles from terminal alkynes

A silver-containing hybrid material is reported as an effective heterogeneous catalyst for the direct synthesis of organic nitriles from terminal alkynes.

In situ synthesis and photocatalytic mechanism of a cyano bridged Cu(i) polymer

A one-dimensional copper(i) nanorod polymer [Cu(L)₂·(CN)]_n (1) (L = 4(3H)-quinazolone), was formed in situ by C–C bond cleavage of acetonitrile.

Copper-catalyzed cyanation of heterocycle C–H bonds with ethyl(ethoxymethylene)cyanoacetate as a cyanating agent and its mechanism

A method for copper-catalyzed cyanation of heterocycles with ethyl(ethoxymethylene)cyanoacetate as a nontoxic and easily available cyanating agent via C–H bond activation has been developed.

Recent developments and applications of cyanamides in electrophilic cyanation

This review summarizes the recent developments and applications of readily accessible cyanamides in the electrophilic cyanation of various nucleophiles.