Novel aryne-mediated synthetic methodologies

Using readily available substrates, a variety of medicinally and biologically important molecules can now be easily prepared by a one-pot transformation involving a reaction with aryne intermediates. The highly reactive arynes have been generated from commercially available or readily prepared o-(trimethylsilyl)aryl triflates and a fluoride source under relatively mild conditions.</p

Effect of the Molybdenum Substrate Shape on Mo₂C Coating Electrodeposition

By electrochemical synthesis in the NaCl-KCl-Li2CO3 (1.5 wt.%)-Na2MoO4 (8.0 wt.%) melt on molybdenum, substrates with different configuration Mo2C coatings with the hexagonal lattice were obtained. The influence of the substrate form on the structure of Mo2C cathodic deposits was studied. The molybdenum carbide coatings on a molybdenum substrate (Mo2C/Mo) show a catalytic activity in the water&#8315;gas shift (WGS) reaction by at least three orders of magnitude higher than that of the bulk Mo2C phase. The catalytic activity remained constant during 500 h for the water&#8315;gas shift reaction

Electrochemical Synthesis of Functional Coatings and Nanomaterials in Molten Salts and Their Application

Nanomaterials are widely used in modern technologies due to their unique properties. Developing methods for their production is one of the most important scientific problems. In this review, the advantages of electrochemical methods for synthesis in molten salts of nanostructured coatings and nanomaterials for different applications were discussed. It was determined that the nanostructured Mo2C coatings on a molybdenum substrate obtained by galvanostatic electrolysis have a superior catalytic activity for the water-gas shift reaction. The corrosion-resistant and wear-resistant coatings of refractory metal carbides on steels were synthesized by the method of currentless transfer. This method also was used for the production of composite carbon fiber/refractory metal carbide materials, which are efficient electrocatalysts for the decomposition of hydrogen peroxide. The possibility to synthesize GdB6 nanorods and Si and TaO nanoneedles by potentiostatic electrolysis was shown

Superconducting Niobium Coatings Deposited on Spherical Substrates in Molten Salts

The interaction of substrates from ceramics, beryllium, and carbopyroceram with the electrolyte for the electrodeposition of niobium coatings was investigated. The corrosion resistance of spherical ceramic and beryllium samples with the protective molybdenum films obtained by magnetron sputtering was studied. The exfoliation of molybdenum film from ceramics and beryllium samples was observed after the experiments due to the interaction of substrates with the melt. It was found that the carbopyroceram did not corrode in the niobium containing melt and this material was chosen as the substrate for the electrodeposition of superconducting niobium coatings. The influence of the oxide ions on the electrochemical behavior of niobium complexes in the NaCl–KCl–NaF–K2NbF7 melt was studied. A special form of the cathode was constructed for the electrodeposition of niobium coatings on spherically shaped substrates. Electrodeposition of the niobium coatings on spheres 10 mm in diameter manufactured from carbopyroceram was carried out at 750 °C with the cathodic current density of 5 × 10−3–2 × 10−2 A·cm−2 and the electrolysis time of 8–12 h. Influence of the cathodic current density on the microstructure of niobium coatings was studied. The roughness, nonsphericity, and superconductive properties of niobium coatings were determined

Synthesis of <i>o</i>‑(Dimethylamino)aryl Ketones, Acridones, Acridinium Salts, and 1<i>H</i>‑Indazoles by the Reaction of Hydrazones and Arynes

A novel, efficient route to biologically and pharmaceutically important <i>o</i>-(dimethylamino)­aryl ketones, acridones, acridinium salts, and 1<i>H</i>-indazoles has been developed starting from readily available hydrazones of aldehydes and <i>o</i>-(trimethylsilyl)­aryl triflates. The reaction proceeds through arynes under mild conditions, tolerates a wide range of functional groups, and provides the final products in good to excellent yields

Palladium-Catalyzed Annulation of Arynes by <i>o</i>‑Halobenzamides: Synthesis of Phenanthridinones

The palladium-catalyzed annulation of arynes by substituted <i>o</i>-halobenzamides produces <i>N</i>-substituted phenanthridinones in good yields. This methodology provides this important heterocyclic ring system in a single step by simultaneous C–C and C–N bond formation, under relatively mild reaction conditions, and tolerates a variety of functional groups

Total Synthesis of Ritterazine B

The first total synthesis of the cytotoxic alkaloid ritterazine B is reported. The synthesis features a unified approach to both steroid subunits, employing a titanium-mediated propargylation reaction to achieve divergence from a common precursor. Other key steps include gold-catalyzed cycloisomerizations that install both spiroketals, and late stage C–H oxidation to incorporate the C7′ alcohol.<br /

Importance of Academic Legacy on Student Success in First- and Second-Semester General Chemistry

This investigation sought to elucidate the influence of students' academic legacy on their prior knowledge and course outcomes providing crucial insights for educators who teach general chemistry. This six-semester analysis involved 6,914 students enrolled in classes across nine Texas universities. Explored were personal circumstances associated with students' successes and failures that influenced performance in on- and off-sequence, first- and second-semester general chemistry (Chem 1 and Chem 2). Students' academic legacy based on their categorization as first generation (neither grandparent nor parent/guardian with a 4-year bachelor's degree), second generation (at least one grandparent or parent/guardian with a bachelor's degree), or third generation (at least one grandparent and at least one parent/guardian hold a bachelor's degree) was investigated. Of the students in the dataset 33.8% (n = 2,340) self-identified as Hispanic. Results for Hispanic and non-Hispanic students indicated that first-generation students struggled more with Chem 1 and Chem 2 than students in the other two legacy groups. As students' academic legacy extended, they were more apt to succeed in general chemistry. Second- and third-generation students demonstrated stronger prior high-school chemistry backgrounds and were enrolled in more advanced mathematics courses. As expected, students with stronger academic backgrounds in chemistry and mathematics scored higher on the diagnostic MUST (Math-Up Skills Test), had greater self-efficacy relative to their preparation to succeed, and reported fewer paid work hours. First-generation students on the average entered with lower diagnostic MUST scores, felt less prepared to succeed, and disclosed a greater need to be employed

Solution-Phase Synthesis of a Diverse Library of Benzisoxazoles Utilizing the [3 + 2] Cycloaddition of in Situ-Generated Nitrile Oxides and Arynes

A library of benzisoxazoles has been synthesized by the [3 + 2] cycloaddition of nitrile oxides with arynes and further diversified by acylation/sulfonylation and palladium-catalyzed coupling processes. The eight key intermediate benzisoxazoles have been prepared by the reaction of <i>o</i>-(trimethylsilyl)­aryl triflates and chlorooximes in the presence of CsF in good to excellent yields under mild reaction conditions. These building blocks have been used as the key components of a diverse set of 3,5,6-trisubstituted benzisoxazoles