One-pot Two-step Method Research Articles

A novel kind of hollow SiO2@g-C3N4@TiO2 microspheres for rapid removal of dyes and antibiotics in water under sunlight

In this paper, using PVP-modified polystyrene microspheres as template, tetrabutyl titanate (TEOT), tetraethyl orthosilicate (TEOS) and melamine as precursor, we developed a facile one-pot two-step method to preparing a novel kind of mesoporous hollow SiO2@TiO2@g-C3N4 ternary composite microspheres with plush surface, in which highly active black titanium dioxide (TiO2) was formed by simple calcination without further chemical reduction treatment. The structure and morphology of the composite microspheres were detailed characterized for understanding the formation mechanism. Research results indicated that the hollow SiO2 microspheres can promote the formation of oxygen vacancies in TiO2, and the ternary combination narrowed the bandgap width of the black hollow composite microspheres to 1.43 eV, thus endowing it with excellent broad-spectrum catalytic performance for rapid photo-degradation of persistent organic pollutants (POPs) such as dyes and antibiotics in water under sunlight. The removal rates of dyes reached more than 70 %, as well as that of antibiotics more than 50 % within one hour. Finally, a plausible catalytic degradation mechanism was discussed.

N-Edited Guanine Isosteres.

Guanine is one out of five endogenous nucleobases and of key interest in drug discovery and chemical biology. Hitherto, the synthesis of guanine derivatives involves lengthy multistep sequential synthesis of low overall diversity, resulting in the quest for innovation. Using a "single-atom skeletal editing" approach, we designed 2-aminoimidazo[2,1-f][1,2,4]triazin-4(3H)-one as a guanine isostere, conserving the biologically important HBA-HBD-HBD (HBA = hydrogen bond acceptor; HBD = hydrogen bond donor) substructure. We realized our design by a simple one-pot two-step method combining the Groebke-Blackburn-Bienaymé reaction (GBB-3CR) and a deprotection reaction to assemble the innovative guanine isosteres in moderate to good yields. Our innovative, diverse, short, and reliable multicomponent reaction synthesis will add to the toolbox of guanine isostere syntheses.

Preparation, characterization and application of maleic anhydride-modified polylactic acid macromonomer based on direct melt polymerization

A one-pot two-step method based on direct melt polymerization (DMP) for the synthesis of polylactic acid (PLA) macromonomer and its further functionalized application has been developed. The first stage of the reaction is a copolycondensation of lactic acid (LA) and maleic anhydride (MAH) to obtain the macromolecule poly(lactic acid-co-maleic anhydride) (PLAM) with reactive double bonds, and the second stage is a radical copolymerization of different acrylates with PLAM to afford the modified PLA functional materials. The influences of the acrylates have been investigated. The results show that the species with substituted methyl groups in acrylate can polymerize relatively stable. On the other hand, the more carbon atoms in the ester segment of acrylate, the higher intrinsic viscosity [η] and terminal decomposition temperature for the acrylate-modified PLAMs. Among six kinds of acrylates used as the third monomer, such as acrylic acid (AA), methyl acrylate (MA), butyl acrylate (BA), methacrylic acid (MAA), methyl methacrylate (MMA), and butyl methacrylate (BMA), the BMA-modified PLAM has the biggest [η] (0.7566 dL/g) and the terminal decomposition temperature (418 °C) for there are more carbon atoms in BMA. Due to excellent reactivity of the intermediate PLAM, the final modified product can have the anticipated properties for the PLA material by the controllable regulating as different purposes. Thus, this strategy as a green and simple method provides well application prospect for PLA materials in industrial plastics, biomedicine etc.

Efficient synthesis and antibacterial activity of N-(o-benzyloxy/hydroxyphenyl) benzohydroxamic acids

A modified one-pot two-step method has been developed to synthesize N-(o-benzyloxyphenyl) benzohydroxamic acids from o-benzyloxy nitrobenzene in good to excellent yields. The synthesized N-(o-benzyloxyphenyl) benzohydroxamic acids were subjected to benzyl deprotection using Pd-C catalyst under H2 gas atmosphere to afford corresponding N-(o-hydroxyphenyl) benzohydroxamic acids. All the synthesized N-(o-benzyloxy/ hydroxyphenyl) benzohydroxamic acids were characterized by 1H-, 13C NMR, FT-IR, UV-Vis., HRMS (ESI) and the structure of the compound 5d was further confirmed by analyzing its X-ray data. The synthesized novel N-(o-benzyloxy/ hydroxyphenyl) benzohydroxamic acids were screened for antibacterial activity against the bacterium Escherichia coli by the serial broth microdilution method using microplate alamar blue assay (MABA). The synthesized derivatives showed significant activity against E. coli.

One-pot Baeyer–Villiger oxidation of cyclohexanone with in situ generated hydrogen peroxide over Sn-Beta zeolites

ε-Caprolactone is traditionally produced through Baeyer-Villiger oxidation of cyclohexanone oxidized by peracids in industry, which inevitably results in large discard acid and environmental pollution. To this end, a green route to ε-caprolactone was developed by coupling the direct generation of hydrogen peroxide from aerobic oxidation of benzhydrol catalyzed by NHPI and Baeyer-Villiger oxidation of cyclohexanone with the in situ hydrogen peroxide over Sn-Beta zeolites in one pot. Molecular oxygen was employed as the terminal oxidant, and the effects of several reaction factors were studied. Compared with one-step process, the one-pot two-step method noticeably improved the selectivity of ε-caprolactone. When the amount of in situ hydrogen peroxide was 0.72 equivalent, the selectivity of ε-caprolactone was obtained 94.8% with 39.2% conversion of cyclohexanone, and the efficiency of H2O2 was up to 51.5%. As compared to the commercial 30 wt% aqueous H2O2 added directly, in situ H2O2 dramatically improved the selectivity of ε-caprolactone and had higher efficiency. Additionally, the catalyst could be easily separated from the reaction solution and reused several times without the remarkable loss of activity.

Hierarchical zeolite enveloping Pd-CeO2 nanowires: An efficient adsorption/catalysis bifunctional catalyst for low temperature propane total degradation

Abstract Volatile organic compounds (VOCs) are significant ozone (O3) and particulate matter (PM) formation precursors and are deleterious to both human health and environment. Catalytic combustion can degrade VOCs to H2O and CO2 without secondary pollution, suggesting a potential sustainable technology for air pollution control. However, the concentration of exhausted VOCs is usually too low for effective decomposition. Herein, a novel adsorption/catalysis bifunctional catalyst, hierarchical silicalite-1 (S-1) zeolite enveloping Pd-CeO2 nanowires (Pd-CeO2NW@S-1), was designed and prepared using a simple one-pot two-step method and applied for the degradation of propane. Pd-CeO2NW@S-1 exhibited superior catalytic activity (T90 decreased to 296 °C) as well as increased thermal and hydrothermal stability (no obviously decrease in activity when treated at 700 °C or reacted with water gas, respectively) compared with Pd-CeO2 nanowires supported on the outer surface of S-1 (Pd-CeO2NW/S-1) and previously reported Pd based catalysts for propane degradation. In addition, the activity over Pd-CeO2NW@S-1 after five reaction cycles just with little decrease and could be restored by a simple regeneration step and without any detection of coke. The remarkable performance over Pd-CeO2NW@S-1 was attributed to the high dispersion of Pd and Ce encapsulated in hierarchical zeolite with superior propane adsorption performance and the special confinement structure according the Mars-van-Krevelen (MvK) mechanism. This confinement adsorption/catalysis bifunctional strategy can be used to design other high-performance catalysts for degradation of VOCs.

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy.

CO2 transformations using a one-pot two-step method are presented herein. The purpose of the method is to give access to a variety of value-added products and notably to generate chiral carbon centers. The crucial first step consists in the selective double hydroboration of CO2 catalyzed by an iron hydride complex. The product obtained with this 4 e- reduction is a rare bis(boryl)acetal, compound 1, which is subjected in situ to three different reactions in a second step. The first reaction concerns a condensation reaction with (diisopropyl)phenylamine affording the corresponding imine 2. In the second and third reaction, intermediate 1 reacts with triazol-5-ylidene (Enders' carbene) to afford compounds 3 or 4, depending on the reaction conditions. In both compounds, C-C bonds are formed, and chiral centers are generated from CO2 as the only source of carbon. Compound 4 exhibits two chiral centers obtained in a diastereoselective manner in a formose-type mechanism. We proved that the remaining boryl fragment plays a key role in this unprecedented stereocontrol. The interest of the method stands on the reactive and versatile nature of 1, giving rise to various complex molecules from a single intermediate. The complexity of a two-step method is compensated by the overall short reaction time (2 h for the larger reaction time), and mild reaction conditions (25 °C to 80 °C and 1 to 3 atm of CO2).

An one-pot two-step automated synthesis of [18F]T807 injection, its biodistribution in mice and monkeys, and a preliminary study in humans.

[18F]T807 is a potent tau protein imaging agent. In order to fulfill the demand from preclinical and clinical studies, we developed an automated one-pot two-step synthesis of this potent tau imaging agent and studied its stability, and dosimetry in mice and monkeys. We also conducted a preliminary study of this imaging agent in humans. Using this one-pot two-step method, the radiochemical yield (RCY) of [18F]T807 was 20.5 ± 6.1% (n = 15) at the end of bombardment (EOB) in a synthesis time of 70±5 min. The chemical and radiochemical purities were >90% and the specific activities were 151 ± 52 GBq/μmol. The quality of [18F]T807 synthesized by this method met the U.S. Pharmacopoeia (USP) criteria. The stability test showed that the [18F]T807 injection was stable at room temperature for up to 4 h after the end of synthesis (EOS). The estimated effective dose of the [18F]T807 injection extrapolated from monkeys was 19 μSv/MBq (n = 2), while the estimated effective doses of the [18F]T807 injection extrapolated from fasted and non-fasted mice were 123 ± 27 (n = 3) and 94 ± 19 (n = 4) μSv/MBq, respectively. This one-pot two-step automated method produced the [18F]T807 injection with high reproducibility and high quality. PET imaging and radiation dosimetry evaluation in mice and Formosan rock monkeys suggested that the [18F]T807 injection synthesized by this method is suitable for use in human PET imaging studies. Thus, this method could fulfill the demand for the [18F]T807 injection in both preclinical and clinical studies of tauopathies, especially for nearby study sites without cyclotrons.

Radiosynthesis and preliminary PET evaluation of 18F-labeled 2-(1-(3-fluorophenyl)-2-oxo-5-(pyrimidin-2-yl)-1,2-dihydropyridin-3-yl)benzonitrile for imaging AMPA receptors

To prompt the development of 18F-labeled positron emission tomography (PET) tracers for the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor, we have prepared 18F-labeled 2-(1-(3-fluorophenyl)-2-oxo-5-(pyrimidin-2-yl)-1,2-dihydropyridin-3-yl)benzonitrile ([18F]8). The radiosynthesis was achieved by a one-pot two-step method that utilized a spirocyclic hypervalent iodine(III) mediated radiofluorination to prepare the 18F-labeled 1-bromo-3-fluorobenzene ([18F]15) intermediate with K18F. A subsequent copper(I) iodide mediated coupling reaction was carried out with 2-(2-oxo-5-(pyrimidin-2-yl)-1,2-dihydropyridin-3-yl)benzonitrile (10) to [18F]8 in 10±2% uncorrected radiochemical yield relative to starting 18F-fluoride with >99% radiochemical purity and 29.6±7.4Gbq/μmol specific activity at the time of injection. PET imaging studies with the title radiotracer in normal mice demonstrated good brain uptake (peak standardized uptake value (SUV)=2.3±0.1) and warrants further in vivo validation.

Para-Selective Cu-Catalyzed C-H Aryloxylation of Electron-Rich Arenes and Heteroarenes.

Cu-catalyzed reaction of phenols with electron-rich arene or heteroarene ligands of unsymmetrical diaryl-λ(3)-iodanes is a key step in the developed one-pot two-step method for intermolecular para-selective C-H aryloxylation of heteroarenes and arenes.

Fully automated one-pot two-step synthesis of 4-[18F]-ADAM, a potent serotonin transporter imaging agent

IntroductionN,N-dimethyl-2-(2-amino-4-[18F]fluorophenylthio)benzylamine (4-[18F]-ADAM, 2) is a potent serotonin transporter (SERT) imaging agent. In order to fulfill the demand of clinical studies, we have developed a fully automated one-pot two-step synthesis of this potent SERT imaging agent. MethodsThe 4-[18F]-ADAM (2) was synthesized using a commercially available GE TRACERlab FN module. Briefly, the precursor, N,N-dimethyl-2-(2,4-dinitrophenylthio) benzylamine (1) in DMSO was reacted with K[18F]/K2.2.2 in a glassy carbon reaction vessel at 120°C for 7.5min followed by reduction of the intermediate with NaBH4/Cu(OAc)2 in EtOH in the same vessel at 80°C for 20min. The reaction mixture was then purified with high-performance liquid chromatography (HPLC) and solid phase extraction (SPE) to give (2). The quality of (2) synthesized by this method was verified by HPLC and TLC as compared to its authentic sample synthesized by two-pot two-step method. ResultsUsing this automated one-pot two-step method, the radiochemical yield (RCY) of (2) was 2.5±0.8% (n=12, EOS) in a synthesis time of 100±6min from EOB with a specific activity of 4.4±1.9Ci/μmol (n=12, EOS). Radioligand (2) was stable over 4h at room temperature. ConclusionsThis fully automated one-pot two-step synthetic method using a commercially available GE TRACERlab FN module could simplify the synthesis of 4-[18F]-ADAM (2) and fulfill its demand for both animal and human studies, especially for study sites without a cyclotron.

Copper-Catalyzedpara-Selective C–H Amination of Electron-Rich Arenes

A one-pot two-step method for para-selective C–H amination of carbocyclic arenes comprises the in situ formation of unsymmetrical diaryl-λ3-iodanes followed by their Cu(I)-catalyzed reaction with a range of N-unprotected amines.

One-pot two-step synthesis of core-shell mesoporous silica-coated gold nanoparticles.

Gold nanoparticles coated with mesoporous silica (Au@mSiO2) have been prepared by a facile one-pot two-step method. The resultant Au@mSiO2 exhibit an ideal core-shell structure with uniform mSiO2 coverage and without any interfacial adhesive layer on the Au surface. Some new explanations on the role that CTAB plays in the synthesis of Au@mSiO2 are discussed.

Facile synthesis and characterization of core/shell Cu–In–Zn–S/ZnS nanocrystals with high luminescence

Cu–Zn–In–S/ZnS (CZIS/ZnS) core/shell nanocrystals (NCs) with high quality have been successfully synthesized via a one-pot two-step method. The photoluminescent properties including emission spectra, photoluminescence quantum yield (PL QY) and PL decay time of the obtained CZIS/ZnS NCs could be tuned by controlling the growth process of ZnS shell. The effect of the amount of Zn added on the growth of ZnS shell was investigated. The shell growth temperature and time for CIZS/ZnS NCs were discussed in detail. A relatively high PL QY of 77% could be achieved under certain reaction condition after systematic study. The crystal structure, morphology, size distribution and chemical composition of CZIS/ZnS NCs were determined by X-ray Diffraction (XRD), selected-area electron diffraction (SAED), low- and high-resolution transmission spectra (TEM) and STEM-EDS, respectively. The photoluminescence mechanisms of the CZIS/ZnS NCs were discussed by time-resolved photoluminescence.

Copper-catalyzed intermolecular C-H amination of (hetero)arenes via transient unsymmetrical λ³-iodanes.

A one-pot two-step method for intermolecular C-H amination of electron-rich heteroarenes and arenes has been developed. The approach is based on a room-temperature copper-catalyzed regioselective reaction of the in situ formed unsymmetrical (hetero)aryl-λ(3)-iodanes with a wide range of primary and secondary aliphatic amines and anilines.

Carbon black functionalized with hyperbranched polymers: synthesis, characterization, and application in reversible CO2 capture

The functionalization of carbon black by grafting of hyperbranched polymers from the surface via self-condensing atom transfer radical polymerization (SC-ATRP) is reported. The surfaces of the pristine carbon black were modified with ATRP initiators using two different methods. The first method uses acid oxidation to place COOH groups on the carbon black surface, followed by the esterification to give ATRP initiators bound to the carbon black surface. Alternatively, ATRP initiators bearing both azido and bromine groups were placed directly on the carbon black surface by nitrene chemistry. The hyperbranched poly(p-chloromethylstyrene) (PCMS) was grafted from the ATRP initiator modified carbon black surfaces using the inimer of p-chloromethylstyrene, and CuCl/CuCl2/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as the catalytic system in N,N-dimethylformamide (DMF). In addition, a one-pot two-step method was developed to graft crosslinked polymers from the carbon black surfaces. The polymerization process was well controlled and the fraction of the grafted polymers on carbon black could be adjusted by changing the polymerization time. The resulting samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The hyperbranched polymers on the carbon black surfaces were quaternized to give an ammonium group on the polymer, and a chloride counterion was subsequently exchanged to give a hydroxide counterion. Under these basic conditions, the ATRP initiators should be attached to the surface using nitrene chemistry rather than acid oxidation, to avoid the hydrolysis of the ester groups that link the grafted polymers to the carbon black surface. The ammonium hydroxide functionalized carbon black materials were utilized for the reversible absorption and desorption of CO2 from ambient air, providing improved absorption/desorption kinetics compared with the commercially available Excellion membrane.

Biomass into chemicals: One-pot two- and three-step synthesis of quinoxalines from biomass-derived glycols and 1,2-dinitrobenzene derivatives using supported gold nanoparticles as catalysts

An efficient and selective one-pot two-step method, for the synthesis of quinoxalines by oxidative coupling of vicinal diols with 1,2-phenylenediamine derivatives, has been developed by using gold nanoparticles supported on nanoparticulated ceria (Au/CeO2) or hydrotalcite (Au/HT) as catalysts and air as oxidant, in the absence of any homogeneous base. Reaction kinetics shows that the reaction controlling step is the oxidation of the diol to α-hydroxycarbonyl compound. Furthermore, a one-pot three-step synthesis of 2-methylquinoxaline starting from 1,2-dinitrobenzene and 1,2-propanediol has been successfully carried out with 98% conversion and 83% global yield to the final product.

Synthesis and biological evaluation of 1-(4-(4-(4-[18F]fluorobenzyl)-1-piperazinyl)butyl)indolin-2-one as dopamine D4 receptor ligand

A potential dopamine D4 receptor ligand, 1-(4-(4-(4-fluorobenzyl)-1-piperazinyl)butyl)indolin-2-one (4) was synthesized through a four-step process and its affinity and selectivity for dopamine D2-like receptors was determined through in vitro receptor binding assay. [18F]4 was prepared using a one-pot two-step method with total radiochemical yield 21.2 % (decay-corrected). The molar radioactivity was around 135 GBq/μmol and the radiochemical purity was greater than 95.5 %. The partition coefficient (Log P) of [18F]4 was determined to be 2.10 ± 0.30 through octanol experiment. The in vivo biodistribution and the competitive distribution of [18F]4 in rat exposed that the tracer passes through blood–brain-barrier (BBB) and may specifically bind to D4 receptor. Metabolite analysis revealed that there was no metabolism of [18F]4 in brain. Conclusively, these preliminary results demonstrated that [18F]4 shows promises as a radioligand for the in vivo study of dopamine D4 receptor.

Efficient and Convenient Synthesis of N3-(Acyloxymethyl)dihydropyrimidinones by a One-Pot Two-Step Method

3,4-Dihydropyrimidinones modified with N3-(acetoxymethyl) and (aroyloxymethyl) groups can be regioselectively obtained in good yields by reactions of 3,4-dihydropyrimidinones with paraformaldehyde and substituted benzoic acids/acetic acid, by a one-pot two-step strategy in the presence of chlorotrimethylsilane. The advantages of this method are the simple procedure, the high regioselectivity of the products, shorter reaction time and the mild reaction conditions. Additionally, this method directly uses acid as acylation reagents and needs not acid anhydride or acyl chloride. Keywords: N3-(Acetoxymethyl)dihydropyrimidinones, N3-(benzoyloxymethyl)dihydropyrimidinones, 3,4-dihydropyrimidinones, Biginelli compounds, one-pot reaction, DHPM, N-alkylation, antihypertensives, adrenergic, cyclocondensation

Easy one-pot access to substituted 2-phenylpyrrolines from 2-pyrrolidinone

An easy access to 2-aryl pyrrolidines is the reduction, stereospecific or not, of the corresponding 2-aryl-pyrroline (5-aryl-3,4-dihydro-2 H-pyrrole). Preparation of the latter has been carried out from 2-pyrrolidinone using an easy one-pot two-step method for the first time.