Yingqi Chen

The construction of single-layer two-dimensional supramolecular organic frameworks in water through the self-assembly of rigid vertexes and flexible edges

Single-layer two-dimensional supramolecular organic frameworks have been constructed in water through three-component self-assembly of rigid cross-shaped vertexes, flexible oligoethylene glycol edges, and cucurbit[8]uril (CB[8]) hosts, driven by CB[8]-encapsulation-enhanced donor–acceptor interaction between the viologen unit and 2,6-dihydroxynaphthalene segment which were peripherally incorporated into the vertex and edge, respectively.

Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes catalyzed by heterogeneous Ps-AlCl3 without solvents

A simple, efficient procedure is proposed for Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes catalyzed by heterogeneous polystyrene-supported aluminum chloride (Ps-AlCl3) under solvent-free conditions. The condensations are carried out smoothly with high yields (87–98%) at 60 °C for 2–4 h in the presence of the Ps-AlCl3 catalyst. The catalyst is characterized by Fourier transfer-infrared spectroscopy (FT-IR). The catalyst is applicable to a wide range of aldehydes, and has excellent recyclability and can be reused several times without loss of activity.

Preparation of SnO2/graphene nanocomposite and its application to the catalytic epoxidation of alkenes with H2O2

The in situ growth of SnO2 nanoparticles on graphene have been achieved via a hydrothermal method and the nanocomposites were used as an efficient catalyst for the epoxidation of alkenes with aqueous hydrogen peroxide in nitrile based systems for the first time. Furthermore, the SnO2/graphene nanocomposites could be readily recovered and reused for at least ten consecutive cycles without significant loss of activity and selectivity.

The direct assembly of Mg–Al LDH nanosheets and Mn(II)–salen complex into sandwich-structured materials and their enhanced catalytic properties

The direct assembly of LDH nanosheets and organic molecules, such as Mn(II)–salen complex, into a sandwich-structured nanocomposite has been achieved via a modified flocculation method. When used as a catalyst, the obtained material has superior thermal stability and catalytic properties over a material prepared using a traditional ion exchange method in the oxidation of 4-picoline.

Improved Synthetic Approach to Tenatoprazole

Abstract An improved synthetic approach to tenatoprazole 1 is described. It started from 2,3,5‐trimethyl‐4‐nitropyridine‐N‐oxide 2 with acetic anhydride via rearrangement and hydrolysis to give 3, Chlorination with SOCl2 yielded 2‐chloromethyl‐3,5‐dimethyl‐4‐nitropyridine hydrochloride 4, then 4 condensed with 2‐mercapto‐5‐methoxy imidazole [4,5‐b]pyridine 5 to give 5‐methoxy‐2‐[(4‐nitro‐3,5‐dimethyl‐2‐pyridinyl)methylthio]imidazole[4,5‐b]pyridine 6. At last the title compound 1 was produced by two methods: 6 was oxidized with MCPBA and then methoxylated with CH3ONa to give 1 and 6 was first methoxylated with CH3ONa and then oxidized with MCPBA to give 1. The overall yield is around 26% for both five‐step syntheses.

Facile, Environmentally Friendly Synthesis of Benzaldehyde and Phenylacetaldehyde Analogs from Readily Available Toluene Derivatives

Abstract A facile environmentally friendly synthesis of bezaldehyde and phenylacetaldehyde analogs from readily available toluene derivatives is described. Oxidation of the styrylamines by H2O2 affords benzaldehydes in moderate yields, while the hydrolysis of styrylamines afforded phenylacetaldehyde analogs in good yields.

Facile construction of leaf-like WO3 nanoflakes decorated on g-C3N4 towards efficient oxidation of alcohols under mild conditions

Herein, a well-defined nanostructure with leaf-like WO3 nanoflakes decorated on g-C3N4 was constructed via a facile impregnation and subsequent annealing method. The prepared WO3/g-C3N4 exhibited excellent catalytic activity for the selective oxidation of alcohols under mild conditions, and satisfactory yields to the corresponding carbonyl compounds were achieved without using non-green additives and organic solvents. It was found that the enhanced catalytic activity could be attributed to the enlarged specific surface area, the well-defined nanostructure, and the strong interactions between WO3 and g-C3N4. The distribution of WO3 nanoflakes on the g-C3N4 support increased the number of catalytically active sites for this reaction. XPS analysis suggested that a synergistic electron effect occurred because of the electron transfer from g-C3N4 to WO3. Moreover, the effects of reaction temperature, reaction time, oxidant amount and catalyst dosage on catalytic activity were investigated. Recycle studies showed that the catalyst could be readily recovered and no obvious decrease in catalytic efficiency was observed after seven cycles. The present catalytic system can afford a wide substrate scope for both aryl and alkyl alcohols with superior conversion and selectivity. Also, a plausible reaction mechanism was proposed to better illustrate the catalytic process. This work might provide a facile construction of a well-defined WO3/g-C3N4 catalyst for the selective oxidation of alcohols using a sustainable approach.

Color conversion of the magnetically separable Al/Fe oxide RNGO in the selective oxidation of benzyl alcohol induced the observation of its morphology change

Herein, via integrating the merits of Fe-based nanoparticles and graphene oxide, magnetic Al/Fe oxide nanoparticles implanted on reduced N-doped graphene oxide (Al/Fe oxide RNGO) were synthesized by solvothermal reaction followed by thermal annealing with a particular temperature and hold time. The synthesized catalyst exhibited excellent performance with more than 80% yield of the desired product benzaldehyde achieved within a 2-hour reaction time. Due to its distinctive magnetism, the material can easily be separated and recycled for subsequent runs. It also demonstrated exceptional stability and recyclability with regard to its performance in a lifetime test without significant capacity or activity loss. The most remarkable finding was the observation of a color shift during the lifetime test due to the change in the morphology, which was further connected with the catalytic performance; initially, a chaotic structure and a comparable inferior catalytic activity were obtained, whereas a waffle or pastry state and a relatively superior activity were observed later. An additional reference without reactants did not display this morphology change; this result supported the employment of the catalyst in the reaction and provided a new alternative methodology to deduce and verify the mechanism.

Synthesis and Antimicrobial Evaluation of Fire Ant Venom Alkaloid Based 2-Methyl-6-alkyl-Δ1,6-piperideines

The first synthesis of 2-methyl-6-pentadecyl-Δ1,6-piperideine (1), a major alkaloid of the piperideine chemotype in fire ant venoms, and its analogues, 2-methyl-6-tetradecyl-Δ1,6-piperideine (2) and 2-methyl-6-hexadecyl-Δ1,6-piperideine (3), was achieved by a facile synthetic method starting with glutaric acid (4) and urea (5). Compound 1 showed in vitro antifungal activity against Cryptococcus neoformans and Candida albicans with IC50 values of 6.6 and 12.4 μg/mL, respectively, and antibacterial activity against vancomycin-resistant Enterococcus faecium with an IC50 value of 19.4 μg/mL, while compounds 2 and 3 were less active against these pathogens. All three compounds strongly inhibited the parasites Leishmania donovani promastigotes and Trypanosoma brucei with IC50 values in the range of 5.0-6.7 and 2.7-4.0 μg/mL, respectively.