Cyanation Reaction Research Articles

Recent Developments in the Biosynthesis of Cu-Based Recyclable Nanocatalysts Using Plant Extracts and their Application in the Chemical Reactions.

Copper nanoparticles (NPs) are one of the most commercialized nanomaterials. From the standpoint of nanotechnology copper-based nanostructured materials have many applications in biological process, folk medicine, electronics, and industrial fields. With growing concern regarding the energy crisis and problems of chemical and physical procedures to prepare the metal nanoparticles, efforts for alternative traditional chemistry attracted particular considerations. A widespread of researches have studied on biological methods which do not generate hazardous waste and therefore, don't need the purification processes. Plants could be remarkably valuable to exploring the biogenic synthesis of metal nanoparticles. The aim of this review is to provide further insight in to connections between plant extracts and synthesis of copper NPs. The utilization of living plants for biosynthesis of metal nanoparticles (MNPs) is a cost-effective and eco-friendly procedure. To date, the obtained results demonstrated several aspects of the plant physiology and their relations to nanoparticle synthesis. This work describes the state of the art and future challenges in green synthesis of copper NPs. This review has proven recent elevation in the green synthesis of Cu NPs, CuO NPs, Cu2 O NPs, CuS NPs, CuAl2 O4 and immobilized copper nanoparticles on the numerous supports such as Natrolite, bentonite, perlite, ZnO, MgO, MnO2 , reduced graphene oxide (RGO), and Fe3 O4 by a wide range of plant extracts. Therefore, detailed description of green synthesis and stabilizing agents concerning copper nanoparticles using these green sources is presented. Also, the catalytic activities of synthesized Cu-based recyclable nanocatalysts using various plant extracts in several chemical reactions such as oxidation, reduction, hydration, cyanation, cycloaddition, and coupling reactions were consciously investigated.

Nickel-Catalyzed Cyanation of Benzylic and Allylic Pivalate Esters.

A nickel-catalyzed cyanation reaction of benzylic and allylic pivalate esters is reported using an air-stable Ni(II) precatalyst and substoichiometric quantities of Zn(CN)2. Alkene additives were found to inhibit catalysis, suggesting that avoiding β-hydride elimination side reactions is essential for productive catalysis. An enantioenriched allylic ester undergoes enantiospecific cross-coupling to produce an enantioenriched allylic nitrile. This method was applied to an efficient synthesis of (±)-naproxen from commercially available starting materials.

Heterogeneous Organocatalysis for Photoredox Chemistry

Photoredox catalysis is a tool enabling a wide variety of chemical reactions with high selectivity under mild conditions of visible light. In this Review, we summarize recent experiments which use heterogeneous, covalent, metal-free semiconductors with adjustable reactivity to drive such reactions. This class started with mesoporous graphitic carbon nitride, then continued with poly(heptazine imides), but is meanwhile extended to other polymers and solid-state organics with conjugated electron system. Because of the high thermal and chemical stability, as well as adjustable conduction and valence band positions, the reaction space could be expanded to many organic reactions, such as photocatalytic synthesis of organosulfur compounds, or unconventional halogenation and cyanation reactions. Performance of carbon nitrides and homogeneous systems in certain reactions was compared in the present Review.

Immobilization of an Aminobisphosphine–PdII Complex Over Graphene Oxide: an Efficient and Reusable Catalyst for Suzuki–Miyaura, Ullmann Coupling and Cyanation Reactions

AbstractInvited for the cover of this issue is the group of MaravanjiàS. Balakrishna from the Indian Institute of Technology Bombay, India. The cover image shows a homogeneous catalyst on a heterogeneous surface used for organic transformations.

Front Cover: Immobilization of an Aminobisphosphine–PdII Complex Over Graphene Oxide: an Efficient and Reusable Catalyst for Suzuki–Miyaura, Ullmann Coupling and Cyanation Reactions (Eur. J. Inorg. Chem. 29/2018)

Front Cover: Immobilization of an Aminobisphosphine–Pd^II Complex Over Graphene Oxide: an Efficient and Reusable Catalyst for Suzuki–Miyaura, Ullmann Coupling and Cyanation Reactions (Eur. J. Inorg. Chem. 29/2018)

Autophagy induces protein carbamylation in fibroblast-like synoviocytes from patients with rheumatoid arthritis.

Autophagy is a homeostatic and physiological process that promotes the turnover of proteins and organelles damaged in conditions of cellular stress. We previously demonstrated that autophagy represents a key processing event creating a substrate for autoreactivity, which is involved in post-translational changes and generation of citrullinated peptides, recognized by the immune system in RA. In this study, we analysed whether autophagy is involved in other post-translational changes that can generate autoantigens, focusing on carbamylation processes. Carbamylation is a nonenzymatic post-translational modification, in which homocitrulline is generated by the reaction of cyanate with the primary amine of lysine residues; carbamylated peptides may accumulate during inflammation conditions. The role of autophagy in the generation of carbamylated proteins was evaluated in vitro in fibroblasts as well as in synoviocytes from RA patients, treated with 5 μM tunicamycin or 200 nM rapamycin; the correlation between autophagy and carbamylated proteins was analysed in mononuclear cells from 30 naïve early-active RA patients. Our results demonstrated that cells treated with tunicamycin or rapamycin showed a significant increase of carbamylated proteins. Immunoblotting and immunoprecipitation experiments identified vimentin as the main carbamylated protein. Furthermore, a correlation was found between autophagy and carbamylation levels in mononuclear cells of naïve RA patients. These data indicate that autophagy is able to induce in vitro carbamylation processes, and in vivo appears to be related to an increase in carbamylation during RA. These observations introduce a new pathogenetic mechanism of disease, which could contribute to more accurate monitoring of patients.

New trends and applications in cyanation isotope chemistry.

In this review, newly developed cyanation methods are evaluated in regards to their usefulness in synthetic isotope chemistry. In combination with already established protocols in 13/14 C- or 11 C-isotope chemistry, this manuscript should help isotope scientists to choose the best possible method for their scientific cyanation problem, but with the main focus on 14 C-applications. Perhaps, most promising of the described novel cyanation reaction is the decarboxylation-cyanation-hydrolysis approach which makes a 1-step late-stage functionalization procedure possible.

Immobilization of an Aminobisphosphine–PdII Complex over Graphene Oxide: An Efficient and Reusable Catalyst for Suzuki–Miyaura, Ullmann Coupling and Cyanation Reactions

The grafting of an aminobis(phosphine)–PdII complex (PNP–PdII) [PdCl2{(Ph2P)2N(CH2)3Si(OMe)3}] (2) on graphene oxide (GO) has been carried out by a condensation reaction between methoxysilane groups of 2 and hydroxyl groups of GO. The composite material was characterized by FTIR spectroscopy , solid‐state 31P NMR spectroscopy, SEM, TEM, XPS and ICP‐AES techniques. All these tools support the clean immobilization of compound 2 on GO. The composite material showed high catalytic activity in Suzuki–Miyaura, Ullmann coupling and cyanation reactions. The heterogeneity of the composite was confirmed by a hot filtration test. The immobilized PNP–PdII shows comparable activity to its homogeneous analogue 2. The recycling ability of the catalyst was examined for five consecutive runs, which showed little or no reduction in its catalytic efficiency.

C(sp3)−H Cyanation Promoted by Visible‐Light Photoredox/Phosphate Hybrid Catalysis

Inspired by the reaction mechanism of photo-induced DNA cleavage in nature, a C(sp3 )-H cyanation reaction promoted by visible-light photoredox/phosphate hybrid catalysis was developed. Phosphate radicals, generated by one-electron photooxidation of phosphate salt, functioned as a hydrogen-atom-transfer catalyst to produce nucleophilic carbon radicals from C(sp3 )-H bonds with a high bond-dissociation energy. The resulting carbon radicals were trapped by a cyano radical source (TsCN) to produce the C-H cyanation products. Due to the high functional-group tolerance and versatility of the cyano group, the reaction will be useful for realizing streamlined building block syntheses and late-stage functionalization of drug-like molecules.

Green Synthesis of Palladium Nanoparticles: Applications in Aryl Halide Cyanation and Hiyama Cross-Coupling Reaction Under Ligand Free Conditions

In the current work, palladium nanoparticles (Pd NPs) were prepared from palladium acetate biogenically using the aqueous-ethanolic extract of black pepper (Piper nigrum) and characterized by various analytical techniques like XRD, FE-SEM, EDS, TEM, ATR-IR, UV–Vis spectroscopy, BET, TGA and ICP-OES analysis. The reduction of Pd(II) to Pd(0) is achieved by the action of various phytochemicals present in the black pepper extract like phenols, acids, pellitorine, ethyl piperonyl cyanoacetate, piperine and N-isobutyl-tetradeca-2,4-dienamide. The biosynthesized Pd NPs shown excellent catalytic activity in aryl halide cyanation and Hiyama cross-coupling reactions. Also, less toxic potassium hexacyanoferrate(II) trihydrate was used as cyanide source in aryl halide cyanation and Hiyama cross-coupling was performed under fluoride free condition. Both reactions proceeded well with Pd NPs under ligand free circumstances to give good to excellent yields. The Pd NPs were recovered after each reaction and recycled up to five times in aryl halide cyanation and ten times in Hiyama cross-coupling without considerable loss in the activity. Green synthesis of palladium nanoparticles: applications in aryl halide cyanation and Hiyama cross-coupling reaction under ligand free conditions.

Molecular Structure of Isocyanic Acid, HNCO, the Imide of Carbon Dioxide.

Isocyanic acid, HNCO, the imide of carbon dioxide, was prepared by reaction of stearic acid and potassium cyanate (KOCN) at 60 °C in a sealed, thoroughly dried reactor. Interestingly, its crystal structure, solved by X-ray single crystal diffraction at 123(2) K, shows a group-subgroup relation for the NCO- anion to carbon dioxide: (for CO2, cP12, Pa3̅, a = 5.624(2) Å, 150 K, C-O 1.151(2) Å; for HNCO, oP16, Pca21, a = 5.6176(9), b = 5.6236(8), c = 5.6231(7) Å, 123(2) K). Precise positions of H, N, C, and O were determined by DFT calculations with WIEN2k leading to interatomic distances C-O 1.17, C-N 1.22, N-H 1.03, and -N-H···N 2.14 Å, and the interatomic angle N-C-O 171°.

Transition-Metal-Catalyzed Cyanation by Using an Electrophilic Cyanating Agent, N-Cyano-N-phenyl-p-toluenesulfonamide (NCTS).

The ability to introduce a nitrile group into a biologically active compound is very useful in organic synthesis, owing to the importance of nitrile groups in transformations and tuning molecular properties. To date, nucleophilic cyanation has been the most used strategy for this purpose, whilst electrophilic cyanation reactions are less developed. Recently, the electrophilic cyanation reagent N-cyano-N-phenyl-p-toluenesulfonamide (NCTS) has received increasing attention, owing to its superior properties in terms of safety and practicality. This Focus Review summarizes recent progress in transition-metal-catalyzed cyanation reactions that use NCTS.

Rhodium‐Catalyzed ortho‐Cyanation of 2‐Aryl‐1,2,3‐triazole: An Alternative Approach to Suvorexant

A rhodium‐catalyzed ortho‐cyanation protocol for 2‐aryl‐1,2,3‐triazole has been developed by using N‐cyano‐N‐phenyl‐p‐toluensulfonamide (NCTS) as an environmentally friendly cyanide source. This simple cyanation reaction provides a new protocol for the diversification of benzonitriles in moderate to good yields and tolerates useful functional groups. In addition, the method was used to synthesize 5‐methyl‐2‐(2H‐1,2,3‐triazol‐2‐yl)benzoic acid, which is the key intermediate of suvorexant.

Manganese‐Catalyzed C−H Cyanation of Arenes with N‐Cyano‐N‐(4‐methoxy)phenyl‐p‐toluenesulfonamide

AbstractA manganese‐catalyzed C−H cyanation reaction of arenes has been developed using N‐cyano‐N‐(4‐methoxy)phenyl‐p‐toluenesulfonamide as the cyanating agent. The reaction proceeds smoothly with high regioselectivity to provide monocyanated products in satisfactory yields.

A metal-free direct C (sp3)-H cyanation reaction with cyanobenziodoxolones.

A metal-free protocol of direct C(sp3)-H cyanation with cyanobenziodoxolones functioning as both cyanating reagents and oxidants was developed. Unactivated substrates, such as alkanes, ethers and tertiary amines, were thereby transformed to the corresponding nitriles in moderate to high yields. Mechanistic studies indicated that the cyanation proceeded with two potential pathways, which is highly dependent on the substrates: (1) a free radical case for alkanes and ethers and (2) an oxidative case for tertiary amines.

Copper-catalyzed amination of an α-C(sp3)-H bond in inactivated ethers to synthesize α-aminonitriles.

A copper-catalyzed functionalization of inert cyclic ethers was developed to provide α-aminonitriles via a cascade oxidation/amination/ring-opening/cyanation reaction. A series of highly versatile α-aminonitriles were obtained from primary or secondary anilines, and heterocyclic and aliphatic amines with high yields. This process features excellent functional group tolerance, a broad substrate scope, and high activity under ambient conditions.

Recent Advances in the Synthesis of Aryl Nitrile Compounds

AbstractAryl nitriles are widely found in natural products, pharmaceuticals, agrochemicals, dyes, and herbicides. Moreover, because the cyano group can be easily converted into various functional groups, aryl nitriles are important intermediates in synthetic organic chemistry. Consequently, the development of new methodologies for the synthesis of aryl nitriles is of significant interest. The traditional methods for their synthesis include Sandmeyer reactions, Rosenmund–von Braun reactions, as well as dehydration reactions of aldoximes and amides. In recent years, numerous efforts have been devoted to transition metal‐catalyzed cyanation reactions of aryl (pseudo)halides, organometallic reagents and aryl C–H bonds. A number of cyanating reagents have been explored for such transformations, including metal cyanides and organic cyano group sources. In addition, styrenes and aryl‐substituted alkynes are successfully converted into aryl nitriles through carbon‐carbon double or triple bond cleavage. Various benzylic compounds have also been used for the synthesis of aryl nitriles, such as benzylic halides, alcohols, amines and azides. Furthermore, the direct conversion of the methyl group of toluene derivatives into a cyano group has also drawn attention. In this critical review, we summarize the recent developments and useful applications in this field and reaction mechanisms are also briefly discussed.magnified image

Bronsted Basic Ionic Liquid as Catalytic and Reusable Media for Conjugate Cyanation of CF3‐Substituted Alkylidenemalonates Using Acetone Cyanohydrin

AbstractA new class of CF3 substituted alkylidenemalonates were synthesized and used as a substrate for conjugate cyanation reaction. Ionic liquid has been used as an organocatalyst under solvent‐free and mild reaction conditions. The present protocol exhibited remarkable catalytic activity using a favourable cyanide source i. e. acetone cyanohydrin. Excellent yields were obtained for a wide range of substrates and the high reactivity is presumptively attributed to the basicity of an ionic liquid used. Mechanistic insights were studied using NMR spectroscopy and a probable catalytic cycle was proposed.

Pd-Catalyzed Cyanation of (Hetero)Aryl Halides by Using Biphosphine Ligands.

Tetraadamantylbiphosphine (TABP; L1), which showed superior activity in the palladium-catalyzed cyanation of 4-chloroanisole compared to standard phosphines, was synthesized as a new ligand. The generality of the new catalytic system was shown by the cyanation reaction of approximately 30 (hetero)aryl halides including hindered, electron-rich, and electron-poor aryl chlorides. These reactions constitute the first examples of using biphosphine ligands in Pd-catalyzed coupling reactions.

Nickel‐Catalyzed Cyanation of Aryl Chlorides and Triflates Using Butyronitrile: Merging Retro‐hydrocyanation with Cross‐Coupling

AbstractWe describe a nickel‐catalyzed cyanation reaction of aryl (pseudo)halides that employs butyronitrile as a cyanating reagent instead of highly toxic cyanide salts. A dual catalytic cycle merging retro‐hydrocyanation and cross‐coupling enables the conversion of a broad array of aryl chlorides and aryl/vinyl triflates into their corresponding nitriles. This new reaction provides a strategically distinct approach to the safe preparation of aryl cyanides, which are essential compounds in agrochemistry and medicinal chemistry.