Microwave-assisted simple, one-pot, four-component synthesis of 2,4,6-triarylpyrimidines under solvent-free conditions

2,4,6-Triarylpyrimidines are synthesized via a simple, one-pot, four-component reaction between aryl methyl ketones, benzaldehydes, aromatic nitriles, and hydroxylamine under microwave irradiation and solvent-free conditions in good to excellent yields.     

Chiral diethylzinc complexes with diamine ligands: synthesis, crystal structure and enantioselective solvent-free alkylation

In search for conglomerates of stereochemically labile organometallic reagents, three new complexes between diethylzinc and diamine ligands have been synthesized and structurally characterized by single-crystal X-ray diffraction methods. Ligands include N,N,N′,N′-tetraethylethylenediamine (teeda), N-isopropyl-N,N′,N′-trimethylethylenediamine (itmeda), and (−)-sparteine (spa). Diethylzinc forms monomeric complexes, exhibiting a distorted tetrahedral coordination geometry around zinc in all three complexes, viz. [ZnEt₂(teeda)] (1), [ZnEt₂(itmeda)] (2), and [ZnEt₂(spa)] (3). Both 1 and 2 are stereochemically labile and exhibit chiral complexes, displaying different types of conformational chirality, but they form racemic crystals. By using the chiral crystals of 3 in a nucleophilic addition to benzaldehyde in the absence of solvent at low temperature, an increase in ee from approximately 8 to 10% was obtained (compared to the same reaction in solution). It thus seems feasible, not only to retain the enantioselectivity obtained in solution, but perhaps even to increase the ee by using solventless reactions.     

An efficient, catalyst- and solvent-free, four-component, and one-pot synthesis of polyhydroquinolines on grinding

An efficient synthesis of polyhydroquinolines is achieved via a four-component reaction of aldehydes, dimedone, active methylene compounds, and ammonium acetate in one-pot under solvent-free conditions at room temperature on grinding. The present method does not involve any hazardous organic solvent or catalyst. The key advantages are the short reaction time, high yields, simple workup, and purification of products by non-chromatographic methods, i.e., by simple recrystallization from ethanol.     

Microwave-assisted efficient, one-pot, three-component synthesis of 3,5-disubstituted 1,2,4-oxadiazoles under solvent-free conditions

A novel synthesis of 1,2,4-oxadiazoles is described from a one-pot, three-component reaction between nitriles, hydroxylamine, and aldehydes under microwave irradiation and solvent-free conditions in excellent yields.     

Efficient one-pot synthesis of 14-substituted-14H-dibenzo[a,j]xanthenes using boric acid under solvent-free conditions

<正>Boric acid efficiently catalysed the one-pot reaction of alkyl or aryl aldehydes with 2-naphthol to afford the corresponding 14- alkyl-or aryl-14H-dibenzo[a,j]xanthenes in good yields under solvent-free conditions.     

Dowex-promoted general synthesis of N,N′-disubstituted-4-aryl-3,4-dihydropyrimidinones using a solvent-free Biginelli condensation protocol

Dowex-50W ion exchange resin-promoted solvent-free heating of an intimate mixture of an aldehyde, an active methylene compound and N,N′-dimethylurea furnished the title compounds in moderate to good yields.     

Hydrothermal synthesis of TiO2 nanorods: formation chemistry,growth mechanism,and tailoring of surface properties for photocatalytic activities

Titanium dioxide (TiO₂) is one of the best semiconductor photocatalysts with optical band gap of 3.2 eV. The optical band gap and photocatalytic properties could be further tuned by tailoring shape, size, composition, and morphology of the nanostructures. Hydrothermal synthesis methods have been applied to produce well-controlled nanostructured TiO₂ materials with different morphologies and improved optoelectronic properties. Among various morphologies, one-dimensional (1D) TiO₂ nanostructures are of great importance in the field of energy, environmental, and biomedical because of the directional transmission properties resulting from their 1D geometry. Particularly, TiO₂ nanorods (NRs) have gained special attention because of their densely packed structure, quantum confinement effect, high aspect ratio, and large specific surface area that could specially improve the directional charge transmission efficiency. This results in the effective photogenerated charge separation and light absorption, which are really important for potential applications of TiO₂-based materials for photocatalytic and other important applications. In this review, hydrothermal syntheses of TiO₂ NRs including the formation chemistry and the growth mechanism of NRs under different chemical environments and effects of various synthesis parameters (pH, reaction temperature, reaction time, precursors, solvents etc.) on morphology and optoelectronic properties have been discussed. Recent developments in the hydrothermal synthesis of TiO₂ NRs and tailoring of their surface properties through various modification strategies such as defect creation, doping, sensitization, surface coating, and heterojunction formation with various functional nanomaterials (plasmonic, oxide, quantum dots, graphene-based nanomaterials, etc.) have been reported to improve the photocatalytic activities. Furthermore, applications of TiO₂ NRs/tailored TiO₂ NRs as superior photocatalysts in degradation of organic pollutants and bacterial disinfection have been discussed with emphasis on mechanisms of action and recent advances in the fields.     

One-pot synthesis of orthogonally protected sugars through sequential base-promoted/acid-catalyzed steps: A solvent-free approach with self-generation of a catalytic species

A varied set of solvent-free, one-pot synthetic sequences were developed to carry out the orthogonal protection of saccharide polyols. These sequences are composed of an initial regioselective benzylation, silylation or iodination (under mildly basic conditions), followed by an acid catalyzed protection of two further hydroxyl sites via the generation of a cyclic acetal. These processes allow recycling of the ammonium or pyridinium side products generated in the former step as effective catalytic species for the latter step.     

Solvent-free synthesis of three layered manganese sulfate-oxalates with different pore apertures

Three manganese sulfate-oxalates, namely, H₂pip·Mn₂(SO₄)₂(ox)(H₂O)₂·2H₂O (1), H₃ipa⋅Mn₂(SO₄)(ox)_2.5·H₂O (2), and H₃dpta⋅Mn₂(SO₄)₂(ox)_1.5(H₂O)₃ (3), were prepared under solvent-free conditions, where pip = piperazine, ox = oxalate, ipa = 3,3′-iminobis(N,N-dimethylpropylamine), and dpta = dipropylenetriamine. These compounds have different layered structures intercalated with organic cations. Their pore apertures range from small 8-membered ring (8 MR) to large 12 MR and extra-large 20 MR. The temperature dependence of the magnetic susceptibility of these compounds were also investigated.     

Solvent-free synthesis of new metal phosphites with double-layered,pillared-layered,and framework structures

Three new metal phosphites, formulated as (H₃O)₂·Mn₂(HPO₃)₃ (1), Co(bpy) (H₂O) (HPO₃) (2), and H₂tmpda·Zn₃(HPO₃)₄ (3), have been synthesized under solvent-free conditions, where bpy = 4,4′-bipyridine, and tmpda = N,N,N′,N′-tetramethyl-1,3-propanediamine. Compound 1 has a double-layered structure with a thickness of 5.68 Å. Compound 2 has an inorganic-organic hybrid framework with cobalt phosphite layers pillared by bpy ligands. Compound 3 has a three-dimensional open-framework structure containing 8-ring channels. The temperature dependence of the magnetic susceptibility of compounds 1 and 2 were also investigated.     

Facile temperature-controlled synthesis of hexagonal Zn2GeO4 nanorods with different aspect ratios toward improved photocatalytic activity for overall water splitting and photoreduction of CO2

Single-crystalline hexagonal prism Zn(2)GeO(4) nanorods with different aspect ratios have been prepared via a solution phase route, which exhibits improved photocatalytic activities in overall water splitting and photoreduction of CO(2) due to the low crystal defects, high specific surface area and beneficial microstructure on the catalyst's surface.     

Eco-friendly synthesis of ZnO nanorods using Cycas pschannae plant extract with excellent photocatalytic,antioxidant, and anticancer nanomedicine for lung cancer treatment

The tunable ZnO nanorods (NRs) are produced due to the phytochemicals present in Cycas pschannae leaves which act as reducing and stabilizing agents. The confirmations of the ZnO NRs were validated using different characterization techniques: X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer, Emmett and Teller (BET), scanning electron microscopy–Energy Dispersive X-Ray Analysis (EDX), UV–visible spectroscopy, Raman spectroscopy, and transmission electron microscopy. The ZnO NRs show unique surface area and low particle size. Photocatalytic activity was measured and found to be 50.75% at low concentrations and 78.33% at high concentrations. The antioxidant activity of the ZnO NRs also showed promising results for their use in free radical scavenging. In vitro toxicity studies using zebrafish embryos was performed to evaluate the toxic nature of it and the obtained result confirmed its non-toxic nature. In addition, ZnO anticancer potential was verified using the A549 lung cancer cell line. Cytotoxic assessments of ZnO NRs were performed via 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and neutral red uptake assays to examine the cell death cycle on the A549 lung cancer cell. Dose-dependent apoptosis and necrosis were confirmed by Lactate dehydrogenase (LDH) assay. It was also confirmed that ZnO NRs induce Reactive oxygen species (ROS) and apoptosis inside cancer (A549) cells via different intrinsic gene expression. Thus, based on this research it is evident that an effective ecofriendly, nontoxic potential anticancer drug can be synthesized using C. pschannae leaf extract.     

Homogeneous catalysis,heterogeneous recycling: a new family of branched molecules with hydrocarbon or fluorocarbon chains for the Friedländer synthesis of quinoline under solvent-free conditions

A new family of branched catalysts with hydrocarbon or fluorocarbon chains was used to catalyze Friedländer reaction between 2-aminoarylketones and α-methylene ketones under solvent-free conditions in good to excellent yields. The catalysts exhibit temperature-dependent solubility and such a thermomorphic character allows them to be recovered by filtration conveniently at room temperature and reused at least five times. To some extent, the branched catalysts with hydrocarbon chains are superior to those with fluorocarbon chains, as they are cheaper and more biodegradable.     

Studies toward the total synthesis of di- and sesterterpenes with a dicyclopenta[a,d]cyclooctane skeleton. Construction of a versatile A/B ring building block via a ring-closing metathesis reaction and carbocationic rearrangement

The cyclopentacyclooctane derivative 1, chosen as the key building block in a synthesis of terpenoid ophiobolates and fusicoccins, has been prepared from 2-methylcyclo-pent-2-en-1-one 5. Cyclization of the intermediate 1,9-diene of l,u configuration 10 under metathesis conditions (Grubbs’ catalyst 15) afforded the eight-membered ring product 13, whereas cyclization of the l,l diastereomer 9 produced a seven-membered ring analog 12. Cationic rearrangement of epoxide 26 occurred with methyl group migration to give ketone 27 as the major product.     

New mixed-halide, boron-centered zirconium cluster phases with different cation distributions within a cluster framework: syntheses and structures of A[(Zr6B)ClxI14−x] (A=Na or Cs, 0x4)

Two new mixed-halide zirconium cluster phases have been synthesized by solid-state reactions in sealed tantalum containers from the Zr(IV) halides, elemental Zr and B, and NaI or CsCl, respectively. Single-crystal X-ray data were used to determine the crystal structures of Na[(Zr₆B)Cl_3.9I_10.1], and Cs[(Zr₆B)Cl_2.2I_11.8]. Both phases crystallize in a stuffed version of the [Nb₆Cl₁₄] structure type, orthorhombic, space group Cmca (Na[(Zr₆B)Cl_3.87(5)I_10.13]: a=15.787(2) Å, b=14.109(2) Å, c=12.505(2) Å, Z=4, R1(F)=0.0322 and wR2(F²)=0.0842; Cs[(Zr₆B)Cl_2.16(5)I_11.84]: a=15.696(4) Å, b=14.156(4) Å, c=12.811(4) Å, Z=4, R1(F)=0.0404 and wR2(F²)=0.1031). This structure type is constructed of clusters which contain centered (Zr₆Z) octahedra of the type [(Zr₆Z)X₁₂ⁱX₆^a] with Z=B and X=Cl and/or I. In both structures, chlorine and iodine atoms are randomly (to X-rays) distributed on the inner non-cluster-interconnecting ligand positions, whereas those sites which bridge metal octahedra are solely occupied by iodine. The phase widths for both phases have been found to cover 0x4 for A^I[(Zr₆B)Cl_xI_14−x]. Whereas the sodium cations in Na[(Zr₆B)Cl_xI_14−x] occupy 25% of a site which is octahedrally surrounded by halogen atoms, the larger cations in the cesium-containing phase occupy a 12-coordinate site within the cluster network.     

Preparation of G-CuO NPs and G-ZnO NPs with mallow leaves,investigation of their antibacterial behavior and synthesis of bis(indolyl)methane compounds under solvent-free microwave assisted dry milling conditions using G-CuO NPs as a catalyst

In this study, biogenic copper and zinc oxide nanoparticles (G-ZnONPs and G-CuONPs) were synthesized by the green synthesis method using Malva parviflora L. (Millow) leaf extract and the obtained nanoparticles were characterized in detail with UV-Vis, FTIR, SEM, XRD. The antibacterial properties of the synthesized nanoparticles on gram-positive and gram-negative bacteria were investigated and it was found that the nanoparticles had high antimicrobial activity in the results of the experiments. With the obtained G-CuONPs, the synthesis of bis(indolyl)methanes with the “green” one-pot synthesis using microwave was achieved quickly and with high efficiency, and the thermal behavior of the obtained products was investigated.     

Reaction of oxazirconacycloheptenes with aldehydes mediated by CuCl: one-pot synthesis of tetrahydrofuran derivatives from four different components involving two molecules of the same or different aldehydes, an ethylene and an alkyne

Reaction of zirconacyclopentenes with 2 equiv. of the same aldehydes in the presence of 1 equiv. of CuCl from −78 °C to room temperature afforded tetrahydrofuran derivatives in good isolated yields upon hydrolysis with aqueous 3 N HCl. Oxazirconacycloheptenes, generated in situ from zirconacyclopentenes with one aldehyde was found to be the reactive intermediate. When treated with a second aldehyde and CuCl, an oxazirconacycloheptene gave a tetrahydrofuran derivative comprised of four different components involving an alkyne, an ethylene and two different aldehydes, thus providing the first one-pot synthesis of important tetrahydrofuran derivatives from four components. When bulky aldehydes were used, hydrolysis of the above reaction mixtures afforded 2-hexen-1,6-diols, which could be quantitatively transformed to their corresponding tetrahydrofuran derivatives when treated with stronger aqueous acid (12 N HCl).     

Hydrothermal synthesis and intercalation behavior of a layered titanium phosphate Ti2(H2PO4)(HPO4)(PO4)2 · 0.5C6N2H16, with an extended γ-phase intercalated into organic amine

With a hydrothermal technique, a layered titanium phosphate with the formula Ti₂(H₂PO₄)(HPO₄)(PO₄)₂ · 0.5C₆N₂H₁₆ (denoted TP-J2) has been prepared by treating the Ti/H₃PO₄/H₂O/1-methylpiperazine system directly. The as-synthesized products were characterized by powder X-ray diffraction, CP-MAS solid-state ³¹P NMR spectroscopy, thermogravimetric and differential thermal analyses (TG-DTA). The structure was solved by single-crystal X-ray diffraction analysis and it presents an extended γ-phase intercalated with organic amine. Crystal data: triclinic, , a = 8.106 (2) Å, b = 8.197 (2) Å, c = 11.658 (2) Å.  = 78.32 (3)°, β = 80.85 (3)°, γ = 77.90 (3)°, Z = 2. Additionally, the intercalation behavior of TP-J2 with n-alkyl monoamine (n = 2, 3, 4, 6, 8, 10 and 12) was investigated. Owing to the strong brønsted base, N,N′-dimethylpiperazine, resides in the interlayer, it presented unusual features of TP-J2 in contrast with that of γ-Tip.