Regioselective Access to 3-Aryl-1-aminoisoquinolines via Nickel(I)-Catalyzed C–C and C–N Cascade Coupling Reactions from the Substituted 2-(Cyanomethyl)benzonitriles

Nickel Catalyzed Selective Arylation of Geminal Dinitriles: Direct Access to α-Cyano Carbonyl Compounds

The catalytic intermolecular arylation of disubstituted geminal dinitriles with in situ generated arylnickel complexes is disclosed. This method efficiently provides various all-carbon substituted α-cyanocarbonyl compounds without additives and an inert atmosphere. It also demonstrates the arylation of R-BINOL and S-BINOL derived geminal dinitriles, preserving optical purity. Mechanistic studies proved that the in situ generated organonickel complex is involved in arylation.

Alkaline-Metal-Promoted Divergent Synthesis of 1-Aminoisoquinolines and Isoquinolines

Alkaline-metal-promoted divergent syntheses of 1-aminoisoquinolines and isoquinolines have been reported involving 2-methylaryl aldehydes, nitriles, and LiN(SiMe3)2 as reactants. In addition, the three-component reaction of 2-methylaryl nitriles, aldehydes, and LiN(SiMe3)2 has been developed to furnish 1-aminoisoquinolines. This protocol features readily available starting materials, excellent chemoselectivity, broad substrate scope, and satisfactory yields.

Nickel-Catalyzed Domino Reaction of α-Aryloxyacetonitriles with Arylboronic Acids: Synthesis of 2-Aroylbenzo[b]furans

We disclose the first catalytic domino reaction of α-(2-formylaryloxy)acetonitriles with arylboronic acids, yielding a range of 2-aroylbenzo[b]furans with yields of up to 93%. Ni(acac)2 serves as an effective dual catalyst. The protocol is also applicable to α-(2-acetylphenoxy)acetonitrile, giving rise to 3-methyl-2-aroylbenzo[b]furans. This domino process is efficient, additive-free, and compatible with a variety of aryl boronic acids, including those with CF3, NO2, CN, and CO2Me groups. Mechanistic studies highlight the dual activation facilitated by the nickel catalyst.

Metal-catalyzed reactions of organic nitriles and boronic acids to access diverse functionality

The nitrile or cyano (-CN) group is one of the most appreciated and effective functional groups in organic synthesis, having a polar unsaturated C-N triple bond. Despite sufficient stability and being intrinsically inert, the nitrile group can be easily transformed into many other functional groups, such as amines, carboxylic acids, ketones, etc. which makes it a vital group in organic synthesis. On the other hand, despite several boronic acids having a low level of genotoxicity, they have found wide applicability in the field of organic synthesis, especially in transition metal-catalyzed cross-coupling reactions. Recently, transition-metal-catalyzed cascade additions or addition/cyclization processes of boronic acids to the nitrile group open up exciting and useful strategies to prepare a variety of functional molecules through the formation of C-C, C-N and CO bonds. Boronic acids can be added to the cyano functionality through catalytic carbometallation or through a radical cascade process to provide newer pathways for the rapid construction of various important acyclic ketones or amides, carbamidines, carbocycles and N,O-heterocycles. The present review focuses on various transition-metal-catalyzed additions of boronic acids via carbometallation or radical cascade processes using the cyano group as an acceptor.

Nickel-catalyzed multicomponent reaction of dinitriles and hydrazine hydrochlorides with boronic acids: access to 1,3-diaryl-1H-pyrazol-5-amines and 4,5-dihydropyridazin-3(2H)-ones

Developing efficient methods to accommodate azaheterocycles has been the hotspot field in organic synthesis. Herein, we disclose a facile and expeditious avenue to synthesize 1,3-diaryl-1H-pyrazol-5-amines and 4,5-dihydropyridazin-3(2H)-ones via nickel-catalyzed addition,...

Vibrational spectroscopy and DFT analysis of 4-cyanophenylhydrazine: A potential SERS probe

4-Cyanophenylhydrazine (4-CPH) is an organic synthesis intermediate. To date, several products derived from 4-CPH have been well studied; however, 4-CPH itself has not been extensively investigated. Herein, we performed vibrational and theoretical analyses of 4-CPH. Density functional theory (DFT) calculations were applied to predict the IR and Raman spectra of 4-CPH, which were compared with the experimental spectra. The calculated and experimental spectral results were in good agreement, except for an abnormal transformation of the protonated 4-CPH cyano group (C≡N), which was observed in the theoretical IR spectrum. Several wavefunction analyses revealed that this transformation was due to the protonation-induced depolarization of the molecule. Moreover, we verified the applicability of 4-CPH as a probe for surface-enhanced Raman spectroscopy (SERS). We observed a pH-dependent shift in the cyano bond frequency within the silent region and determined, as a novel discovery, that this shift was induced by 4-CPH protonation. Our results provide considerable, fundamental information that confirms the potential of 4-CPH as a SERS probe.

Ni-catalyzed cascade coupling reactions: synthesis and thermally-activated delayed fluorescence characterization of quinazolinone derivatives

A nickel-catalyzed cascade coupling of 2-(2-(arylcarbonyl)-4-oxoquinazolin-3(4H)-yl)acetonitrile and arylboronic acid for the synthesis of pyrazino-fused quinazolinones has been developed. The TADF effect of 3a in the solid-state was investigated.

Direct synthesis of 2-substituted benzonitriles via alkylcyanation of arynes with N,N-disubstituted aminomalononitriles

An efficient alkylcyanation of in situ generated arynes by N,N-disubstituted aminomalononitriles is described, enabling the direct synthesis of 2-substituted benzonitriles.

Nickel(ii)-catalyzed C–C, N–C cascade coupling of ketonitriles into substituted pyrroles and pyridines

The first example of nickel complexes as effectively catalyst to C–C, N–C cascade coupling of ketonitriles with arylboronic acids, affording 2,5-diarylpyrroles and 2,6-diarylpyridines.

Tandem addition/cyclization for synthesis of 2-aroyl benzofurans and 2-aroyl indoles by carbopalladation of nitriles

Pd-Catalyzed tandem reaction of 2-(2-acylphenoxy)acetonitriles or 2-((2-benzoylphenyl)amino)acetonitrile with arylboronic acids for the synthesis of 2-aroyl benzofurans and 2-aroyl indoles.

Assembly of 1H-isoindole derivatives by selective carbon-nitrogen triple bond activation: access to aggregation-induced emission fluorophores for lipid droplet imaging

A method of selectively activating carbon–nitrogen triple bonds has been developed to access 1H-isoindole AIE fluorophores for lipid droplet imaging.

A novel strategy has been established to assemble a series of single (Z)- or (E)-1H-isoindole derivatives through selectively and sequentially activating carbon–nitrogen triple bonds in a multicomponent system containing various nucleophilic and electrophilic sites. The reaction provides efficient access to structurally unique fluorophores with aggregation-induced emission characteristics. These new fluorophores show fluorescence wavelengths and efficiencies that can be modulated and have excellent potential to specifically light up lipid droplets (LDs) in living cells with bright fluorescence, low cytotoxicity and better photostability than commercially available LD-specific dyes.

Efficient synthesis of spirooxindolyl oxazol-2(5H)-ones via palladium(ii)-catalyzed addition of arylboronic acids to nitriles

A versatile synthesis of spirooxindolyl oxazol-2(5H)-ones and derivatives via palladium(ii)-catalyzed addition of arylboronic acids to nitriles is described.

Rhodium-catalyzed C–H activation/annulation of amidines with 4-diazoisochroman-3-imines toward isochromeno[3,4-c]isoquinolines

Rhodium-catalyzed C–H activation/annulation of amidines with 4-diazoisochroman-3-imines toward 8-amino-5H-isochromeno[3,4-c]isoquinolines with good functional group tolerance.