A general and convenient catalytic synthesis of nitriles from amides and silanes

Efficient catalyst-free direct amidation of non-activated carboxylic acids from carbodiimides

A novel and efficient catalyst- and activating agent-free amidation method via direct amidation of carboxylic acids where carbodiimides act as a reagent instead of an activating agent is reported. The reaction is conducted under non-traditional coupling conditions where a higher temperature is employed. Besides not using stoichiometric ratios of activating agent or catalyst, this approach is made even more attractive by occurring in the presence of the environmentally friendly and recyclable non-toxic solvent of DMSO. A wide variety of benzylic, aliphatic, α,β-unsaturated and aromatic carboxylic acids provide related amides in up to 95% yield. The excellent yield from a gram-scale reaction shows that this application is particularly convenient for larger-scale synthesis applications.

Bioinspired Iron-Catalyzed Dehydration of Aldoximes to Nitriles: A General N-O Redox-Cleavage Method

Inspired by OxdA that operates biocatalytic aldoxime dehydration, we have developed an efficient iron catalyst, Cp*Fe(1,2-Cy₂PC₆H₄O) (1), which rapidly converts various aliphatic and aromatic aldoximes to nitriles with release of H₂O at room temperature. The catalysis involves redox activation of the N-O bond by a 1e^- transfer from the iron catalyst to the oxime. Such redox-mediated N-O cleavage was demonstrated by the isolation of a ferrous iminato intermediate from the reaction of the ketoxime substrate. This iron-catalyzed acceptorless dehydration approach represents a general method for the preparation of nitriles, and it also delivers salicylonitriles by catalyzing the Kemp elimination reaction.

Development of vericiguat: The first soluble guanylate cyclase (sGC) stimulator launched for heart failure with reduced ejection fraction (HFrEF)

In recent years, with improvements in treatments for heart failure (HF), the survival period of patients has been extended. However, the emergence of some patients with repeated hospitalizations due to their worsening conditions and low survival rates followed. Currently, few drugs are available for such patients. Vericiguat was first drug approved for the treatment of symptomatic patients with chronic HF with reduced ejection fraction (HFrEF) to reduce the occurrence of worsening HF. This article provides comprehensive information about vericiguat in terms of drug design and development, structure-activity relationship (SAR), synthesis, pharmacological efficacy, and clinical practice. In addition, insights into the current vericiguat trials and treatments of HF are also discussed.

Preparation of Polyfunctionalized Aromatic Nitriles from Aryl Oxazolines

A selective ortho,ortho'-functionalization of readily available aryl oxazolines by two successive magnesiations with sBu2 Mg in toluene followed by trapping reactions with electrophiles, such as (hetero)aryl iodides or bromides, iodine, tosyl cyanide, ethyl cyanoformate or allylic bromides (39 examples, 62-99 % yield) is reported. Treatment of these aryl oxazolines with excess oxalyl chloride and catalytic amounts of DMF (50 °C, 4 h) provided the corresponding nitriles (36 examples, 73-99 % yield). Conversions of these nitriles to valuable heterocycles are reported, and a tentative mechanism is proposed.

Production of Nitrogen-Containing Compounds via the Conversion of Natural Microalgae from Water Blooms Catalyzed by ZrO2

Utilizing the inherent high nitrogen content in natural microalgae to produce value-added nitrogen-containing compounds such as fatty amides and fatty nitriles is a promising method. Herein, a method for producing value-added fatty amides and nitriles by liquefaction of natural microalgae from water blooms in n-heptane was developed. The effects of temperature, metal oxide catalyst (ZrO₂ , Al₂ O₃ , TiO₂ , ZnO, MgO, CaO), catalyst amount, and reaction time on the preparation of value-added nitrogen-containing compounds were studied. Under the optimized conditions (0.3 g ZrO₂ , 300 °C, 6 h), the total yield of fatty amides was 6.9 wt %, and the yield of fatty nitriles was 1.9 wt %. Compared with the results obtained in the absence of ZrO₂ , after adding ZrO₂ the total yield of fatty acids was reduced by 4.7 wt % (18.5 to 13.8 wt %), while the total yield of fatty amides only increased by 0.9 wt % (6.0 to 6.9 wt %) and fatty nitriles was increased by 1.5 wt % (0.4 to 1.9 wt %). Exploring the role of ZrO₂ by using model compounds (i. e., palmitic acid and palmitamide) revealed that ZrO₂ could promote the dehydration of fatty amides to form fatty nitriles, but had limited effect on the reaction of fatty acid and NH₃ .

One pot synthesis of aryl nitriles from aromatic aldehydes in a water environment

In this study, we found a green method to obtain aryl nitriles from aromatic aldehyde in water. This simple process was modified from a conventional method. Compared with those approaches, we used water as the solvent instead of harmful chemical reagents. In this one-pot conversion, we got twenty-five aryl nitriles conveniently with pollution to the environment being minimized. Furthermore, we confirmed the reaction mechanism by capturing the intermediates, aldoximes.

In a formic acid–H₂O solution (60% : 40%), most aromatic aldehydes react efficiently with hydroxylamine hydrochloride and sodium acetate to form nitriles, where formic acid acts as both catalyst and solvent.

Genomic and Metabolomic Investigation of a Rhizosphere Isolate Streptomyces netropsis WLXQSS-4 Associated with a Traditional Chinese Medicine

Rhizosphere microorganisms play important ecological roles in promoting herb growth and producing abundant secondary metabolites. Studies on the rhizosphere microbes of traditional Chinese medicines (TCMs) are limited, especially on the genomic and metabolic levels. In this study, we reported the isolation and characterization of a Steptomyces netropsis WLXQSS-4 strain from the rhizospheric soil of Clematis manshurica Rupr. Genomic sequencing revealed an impressive total of 40 predicted biosynthetic gene clusters (BGCs), whereas metabolomic profiling revealed 13 secondary metabolites under current laboratory conditions. Particularly, medium screening activated the production of alloaureothin, whereas brominated and chlorinated pimprinine derivatives were identified through precursor-directed feeding. Moreover, antiproliferative activities against Hela and A549 cancer cell lines were observed for five compounds, of which two also elicited potent growth inhibition in Enterococcus faecalis and Staphylococcus aureus, respectively. Our results demonstrated the robust secondary metabolism of S. netropsis WLXQSS-4, which may serve as a biocontrol agent upon further investigation.

Aerobic dehydrogenation of amines to nitriles catalyzed by triazolylidene ruthenium complexes with O2 as terminal oxidant

Pyridyl-substituted mesoionic triazolylidene ruthenium cymene complexes catalyze the oxidation of both aromatic and aliphatic amines to nitriles with high activity and selectivity under benign conditions using dioxygen as the terminal oxidant. Modification on the pyridyl moiety of the ligand scaffold has negligible effect on the catalytic performance, while substituents on the triazolylidene directly affect the catalytic fitness of the metal center, leading to distinct catalytic profiles. Pre-dissociation of the cymene ligand and formation of a solvento analogue further enhances the catalytic activity towards nitrile formation. Variation of reaction conditions provided valuable mechanistic insights and resulted in a highly efficient protocol for nitrile formation with maximum turnover numbers around 10 000. The turnover frequency reaches up to 400 h^-1, providing one of the fastest catalytic systems known to date for this transformation.

NHC-catalyzed silylative dehydration of primary amides to nitriles at room temperature

Herein we report an abnormal N-heterocyclic carbene catalyzed dehydration of primary amides in the presence of a silane. This process bypasses the energy demanding 1,2-siloxane elimination step usually required for metal/silane catalyzed reactions. A detailed mechanistic cycle of this process has been proposed based on experimental evidence along with computational study.

Recent developments in dehydration of primary amides to nitriles

Various dehydration methods available for the direct conversion of amides to the corresponding nitriles have been reviewed.

A Cyanide-Free Synthesis of Acylcyanides through Ru-Catalyzed C(sp3)-H-Oxidation of Benzylic Nitriles

A practical method for generation of acylcyanides devoid of any external cyanide sources is presented that relies on a mild Ru‐catalyzed selective C−H‐oxidation of benzylic nitriles. The starting materials are smoothly generated through condensation of the corresponding carboxylic acid amides using silanes. The obtained acylcyanides can be employed in a plethora of transformation as exemplified to some larger extend in the sequence of C−H‐oxidation‐Tischenko‐rearrangement for the generation of structurally diverse benzoyloxycyanohydrines.

An effective preparation of both 1,3-diketones and nitriles from alkynones with oximes as hydroxide sources

An effective phosphine-catalyzed protocol has been established for the syntheses of 1,3-diketones and nitriles from alkynones with oximes as hydroxide surrogates. This method features the use of a phosphine catalyst, compatibility with various functional groups and ambient temperature, which makes this approach very practical. A plausible mechanism was proposed.

Haridasan R, Das A, Ahmed J, Mandal SK. Primary amides to amines or nitriles: a dual role by a single catalyst

We report the first earth abundant single mononuclear Mn(iii) complex which can selectively and catalytically transform primary amides to nitriles as well as reduce primary amides to amines.

POCN Ni(ii) pincer complexes: synthesis, characterization and evaluation of catalytic hydrosilylation and hydroboration activities

(POCN)Ni(ii) complexes were found to mediate a variety of carbonyl hydroboration reactions, including chemoselective hydroboration of benzaldehyde and hydroborative reduction of amides.

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.

Development and Utilization of a Palladium-Catalyzed Dehydration of Primary Amides To Form Nitriles

A palladium(II) catalyst, in the presence of Selectfluor, enables the efficient and chemoselective transformation of primary amides into nitriles. The amides can be attached to aromatic rings, heteroaromatic rings, or aliphatic side chains, and the reactions tolerate steric bulk and electronic modification. Dehydration of a peptaibol containing three glutamine groups afforded structure–activity relationships for each glutamine residue. Thus, this dehydration can act similarly to an alanine scan for glutamines via synthetic mutation.

Ruthenium-Catalyzed Aerobic Oxidation of Amines

Amine oxidation is one of the fundamental reactions in organic synthesis as it leads to a variety of value-added products such as oximes, nitriles, imines, and amides among many others. These products comprise the key N-containing building blocks in the modern chemical industry, and such transformations, when achieved in the presence of molecular oxygen without using stoichiometric oxidants, are much preferred as they circumvent the production of unwanted wastes. In parallel, the versatility of ruthenium catalysts in various oxidative transformations is well-documented. Herein, this review focuses on aerobic oxidation of amines specifically by using ruthenium catalysts and highlights the major achievements in this direction and challenges that still need to be addressed.

Mechanistic Insight Facilitates Discovery of a Mild and Efficient Copper-Catalyzed Dehydration of Primary Amides to Nitriles Using Hydrosilanes

Metal-catalyzed silylative dehydration of primary amides is an economical approach to the synthesis of nitriles. We report a copper-hydride(CuH)-catalyzed process that avoids a typically challenging 1,2-siloxane elimination step, thereby dramatically increasing the rate of the overall transformation relative to alternative metal-catalyzed systems. This new reaction proceeds at ambient temperature, tolerates a variety of metal-, acid-, or base-sensitive functional groups, and can be performed using a simple ligand, inexpensive siloxanes, and low catalyst loading.

Reduction of Benzolactams to Isoindoles via an Alkoxide-Catalyzed Hydrosilylation

An alkoxide-catalyzed reduction of benzolactams to isoindoles with silanes was realized. With t-BuOK as the catalyst and Ph₂SiH₂ as the reductant, a series of benzolactams containing different functional groups were reduced to the corresponding isoindoles, which could be captured by N-phenyl maleimide to form Diels-Alder products in moderate to good yields. Deuterium labeling studies and the hydrosilylation of benzolactam in DMF indicated that the deprotonation of benzolactams took place at C3 potion during the reduction.

Selective Reductive Removal of Ester and Amide Groups from Arenes and Heteroarenes through Nickel-Catalyzed C-O and C-N Bond Activation

An inexpensive nickel(II) catalyst and a hydrosilane were used for the efficient reductive defunctionalization of aryl and heteroaryl esters through a decarbonylative pathway. This versatile method could be used for the removal of ester and amide functional groups from various organic molecules. Moreover, a scale-up experiment and a synthetic application based on the use of a removable carboxylic acid directing group highlight the usefulness of this reaction.

Nickel-catalyzed reductive defunctionalization of esters and amides to aromatic hydrocarbons

In two recent studies, nickel has been used in the removal of ester and amide groups to afford aromatic hydrocarbons via one-pot reductive activation followed by tandem C–CO bond cleavage–decarbonylation. Isolation and characterization of key intermediates provide insight into this acyl C–O bond activation pathway.

Redox reaction between benzyl azides and aryl azides: concerted synthesis of aryl nitriles and anilines

A unique and novel reaction between benzyl azides and aryl azides is described to synthesize aryl nitriles and anilines concurrently, which is catalyzed with a photoactivated diruthenium complex.