A Molecular Dynamics Study on the Dislocation-Precipitate Interaction in a Nickel Based Superalloy during the Tensile Deformation.

In the present paper, the dislocation-precipitate interaction in the Inconel 718 superalloy is studied by means of molecular dynamics simulation. The atomistic model composed of the ellipsoidal Ni3Nb precipitate (γ″ phase) and the Ni matrix is constructed, and tensile tests on the composite Ni3Nb@Ni system along different loading directions are simulated. The dislocation propagation behaviors in the precipitate interior and at the surface of the precipitate are characterized. The results indicate that the dislocation shearing and bypassing simultaneously occur during plastic deformation. The contact position of the dislocation on the surface of the precipitate could affect the penetration depth of the dislocation. The maximum obstacle size, allowing for the dislocation shearing on the slip planes, is found to be close to 20 nm. The investigation of anisotropic plastic deformation behavior shows that the composite system under the loading direction along the major axis of the precipitate experiences stronger shear strain localizations than that with the loading direction along the minor axis of the precipitate. The precipitate size effect is quantified, indicating that the larger the precipitate, the lower the elastic limit of the flow stress of the composite system. The dislocation accumulations in the precipitate are also examined with the dislocation densities given on specific slip systems. These findings provide atomistic insights into the mechanical behavior of nickel-based superalloys with nano-precipitates.

Three-Component Fusion to Pyrazolo[5,1-a]isoquinolines via Rh-Catalyzed Multiple Order Transformation of Enaminones.

A facile and practical method for the synthesis of fused tricyclic pyrazolo[5,1-a]isoquinolines has been realized via the reactions of enaminones, hydrazine hydrochloride, and internal alkynes. By means of Rh catalysis, the extraordinary high-order bond functionalization, including the transformation of aryl C-H, ketone C═O, and alkenyl C-N bonds in the enaminones, marks the major feature of the cascade reactions. The results disclose the individual advantage of enaminones in the design of novel and efficient synthetic methods.

Catalyst-Free Cascade Annulation of Enaminones and Aryl Diazonium Tetrafluoroboronates for Cinnoline Synthesis and the Anti-Inflammatory Activity Study.

A simple and concise method for the synthesis of cinnolines has been developed by the reactions of readily available enaminones and aryl diazonium tetrafluoroboronates. The reactions run efficiently to provide cinnolines with broad diversity in the substructure by heating in dimethyl sulfoxide without using any catalyst or additive. In addition, the primary investigation of the anti-inflammatory activity of these products leads to the observation of p-chlorobenzoyl (3f) and p-nitrobenzoyl (3j) cinnolines as attractive anti-inflammatory compounds in vitro.

Synthesis of Dihydrochromeno[2,3-b]indoles via an Fe(OTf)3-Catalyzed Cascade Reaction.

A tandem cyclization between 2-(2-aminophenyl)acetonitriles and 2-(hydroxy(aryl)methyl)phenols for the preparation of dihydrochromeno[2,3-b]indole derivatives was successfully developed. The transformation proceeded smoothly in the presence of a catalytic environmentally benign iron salt, and various multisubstituted dihydrochromeno[2,3-b]indoles were synthesized in moderate to high yields.

Synthesis of Trifluoromethyl- and Ester Group-Substituted α-Carbolines via Iron-Catalyzed Tandem Cyclization Reaction.

An efficient approach to prepare trifluoromethyl-α-carbolines and ester group-substituted α-carbolines via the tandem cyclization reaction of 2-(2-aminophenyl)acetonitriles and trifluoromethyl 1,3-diones or ß,γ-unsaturated α-ketoesters was reported. The transformation proceeded smoothly in the presence of catalytic environmental-benign iron salts, which are used to prepare the desired products in moderate to good yields.

Transition metal-catalyzed sp3 C-H activation and intramolecular C-N coupling to construct nitrogen heterocyclic scaffolds.

Nitrogen heterocycles are of great medicinal importance, and the construction of nitrogen heterocyclic scaffolds has been one of the focuses in synthetic organic chemistry. Recently, the strategy of transition metal-catalyzed sp3 C-H activation and intramolecular C-N coupling to construct nitrogen heterocyclic scaffolds has been well developed. Palladium, copper, silver, nickel, cobalt, ruthenium and rhodium catalysis were successfully used for the construction of nitrogen heterocyclic scaffolds, aziridines, azetidines, pyrrolidines, pyrrolidine-2,5-diones, indolines, isoindolines, isoindolinones, tetrahydropyridines, oxazolidinones, oxazinanones, ß-lactams, γ-lactams etc., which have been synthesized by the sp3 C-H activation strategy. Here, we summarize the progress of transition metal-catalyzed sp3 C-H activation/intramolecular C-N bond formation, and introduce both the reaction development and mechanisms in numerous synthetically useful intramolecular sp3 C-H catalytic aminations/amidations.

The synthesis of imidazo[1,5-a]quinolines via a decarboxylative cyclization under metal-free conditions.

An iodine-mediated decarboxylative cyclization was developed from α-amino acids and 2-methyl quinolines under metal-free conditions, affording a variety of imidazo[1,5-a]quinolines with moderate to good yields.

An efficient iron-promoted synthesis of 6H-indolo[2,3-b]quinolines and neocryptolepine derivatives.

A facile and practical method for the preparation of 6H-indolo[2,3-b]quinolines and neocryptolepines was developed under the promotion of the easily available ferric trichloride, affording the desired products with moderate to good yields.

Direct electrochemical imidation of aliphatic amines via anodic oxidation.

Direct electrochemical synthesis of sulfonyl amidines from aliphatic amines and sulfonyl azides was realized with good to excellent yields. Traditional tertiary amine substrates were broadened to secondary and primary amines. The reaction intermediates were observed and a reaction mechanism was proposed and discussed.

Simple and efficient preparation of 2,5-disubstituted oxazoles via a metal-free-catalyzed cascade cyclization.

A practical and simple synthesis of 2,5-disubstituted oxazoles was developed via an iodine-catalyzed tandem oxidative cyclization. A wide range of common commercial aromatic aldehydes can be used as reaction substrates, which displayed excellent functional group compatibility in this reaction.

A novel and efficient methodology for the construction of quinazolines based on supported copper oxide nanoparticles.

A series of quinazolines were synthesized from 2-aminobenzophenones and benzylic amines in good to excellent yields by employing a new heterogeneous catalyst based on the copper oxide nanoparticles supported on kaolin.

A simple and efficient approach to the synthesis of 2-phenylquinazolines via sp(3) C-H functionalization.

A facile and novel approach to the synthesis of 2-phenylquinazolines was developed via a tandem reaction following sp(3) C-H functionalization. Twenty-five examples of 2-phenylquinazolines were obtained from easily available 2-aminobenzophenones and benzylic amines with good to excellent yields.

Facile synthesis of polysubstituted oxazoles via a copper-catalyzed tandem oxidative cyclization.

A highly efficient synthesis of polysubstituted oxazoles was developed via a copper-catalyzed tandem oxidative cyclization. The desired products can be obtained from readily available starting materials under mild conditions. This is an attractive alternative method for the synthesis of oxazole derivatives.

Cascade synthesis of 3-quinolinecarboxylic ester via benzylation/ propargylation-cyclization.

Reactions of 2-amino-aryl alcohols with beta-ketoesters catalyzed by a catalytic amount of FeCl3 via tandem benzylation-cyclization produce the corresponding 3-quinolinecarboxylic esters in good to high yields. Extending this methodology to propargylation-cyclization, 2-nitrophenyl propargyl alcohols with beta-ketoesters catalyzed by FeCl3 and SnCl2 also produce the 4-alkyne-3-quinolinecarboxylic esters. The mechanistic details of this benzylation/propargylation and cyclization cascade process are also discussed.

Investigation of DNA as a catalyst for Henry reaction in water.

Double-stranded DNA of natural origin can be used to facilitate nitro-aldol (or Henry) reaction in aqueous solution.