A mild and green chemistry approach for the synthesis of symmetrical spirooxindole derivatives

A simple and eco-friendly synthesis of the biologically important spirooxindole scaffold was done by the reaction of isatin with activated pyrazolones in the presence of a catalytic amount of p-toluenesulfonic acid in water at room temperature. A variety of symmetrical spirooxindole derivatives were obtained with excellent yields within short reaction time. This method is of great value because of its environmentally benign character, high yield, and easy handling.     

CuO‐CeO2 Nanocomposite: A Highly Efficient Recyclable Catalyst for the Green Synthesis of 1,8‐Dioxooctahydroxanthenes in Water

CuO‐CeO₂ nanocomposite is reported as a highly efficient and recyclable catalyst for the green synthesis of 1,8‐dioxooctahydroxanthenes in water. This catalyst can be recovered by simple filtration and recycled up to 8 consecutive runs without any losing of its efficiency.     

Solvent‐Free Chemoselective Synthesis of 1,1‐Diacetates Catalyzed by Cu(NO3)2 · 3H2O

1,1‐Diacetates have been synthesized by the reaction of a variety of aldehydes with acetic anhydride in the presence of cupric nitrate as catalyst under solvent‐free conditions. Ketones were not converted to the corresponding diacetates under these conditions.     

Synthesis,characterization and theoretical evaluations of HMDS promoted chemoselective O-alkylation of uracils

The sodium salts of the conjugated bases of uracils undergo highly chemoselective O⁴-monoalkylation when treated with various alkyl halides in dry DMF, while the use of methyl iodide results in N¹+N³-dimethylation. Theoretical evaluations of the chemo- and regioselectivity along with X-ray crystallographic data are presented.     

Synthesis of benzaldehyde-functionalized LewisX trisaccharide analogs for glyco-SAM formation

LewisX (Le^x) antigen based carbohydrate–carbohydrate interactions are mediated by complexation of metal ions. Although theoretical studies about the influence of participating hydroxyl groups in the Le^x trisaccharide head group (Galβ(1-4)[Fucα(1-3)]GlcNAc) could gave same rudimental information about the basic mechanism behind this interaction, a little is known about orientation and configuration of the hydroxyl groups required for the specific interaction mediated by Ca²⁺ complexation. Therefore, there is a need of non-natural derivatives to provide detailed information about the requirements for hydroxyl group arrangement in Le^x head group surface plasmon resonance and gold nanoparticle techniques have shown to be powerful tools to investigate carbohydrate–carbohydrate interactions. Benzaldehyde-functionalized glycans can be used for attachment to both gold nanoparticles and surface plasmon resonance sensor surfaces. Therefore, seven benzaldehyde equipped Le^x analogs including the natural trisaccharide were synthesized utilizing convergent approach. The derivatives were applied in ongoing carbohydrate–carbohydrate interaction studies by surface plasmon resonance experiments to prove theoretical postulate about the structural requirements of hydroxyl group arrangements in Le^x trisaccharides.     

Evaluation of the cyclotron production of 165Er by different reactions

Erbium-165 with 10.3 h physical half-life decays completely by electron capture to the ground state of stable isotope ¹⁶⁵Ho and it is an ideal radio lanthanide for Auger electron therapy. Excitation function of ¹⁶⁵Er via ^natEr(p,x)¹⁶⁵Tm → ¹⁶⁵Er, ¹⁶⁶Er(p,2n)¹⁶⁵Tm → ¹⁶⁵Er, ¹⁶⁵Ho(p,n)¹⁶⁵Er and ¹⁶⁵Ho(d,2n)¹⁶⁵Er reactions were calculated using ALICE/ASH (Hybrid and GDH models) and EMPIRE 3.1 codes and then were compared with the reported measurement by experimental data and TENDL-2011. Physical yield and target thickness were evaluated with attention to excitation function, stopping power and SRIM code. ¹⁶⁵Er was produced using the sedimentation technique through the ^natEr (p,x)¹⁶⁵Tm → ¹⁶⁵Er reaction. The deposited target was irradiated with 15 MeV proton beams at 20 μA current for 1 h. The ¹⁶⁵Tm production yield was 26 MBq/μA h at the end of bombardment.     

Fabrication of ozone gas sensor based on FeOOH/single walled carbon nanotube-modified field effect transistor

A novel ozone (O₃) sensor is fabricated using commercial metal oxide field effect transistor (MOSFET), modified with single-walled carbon nanotubes (SWCNTs). In this study, integrated circuit (IC: BS250) was selected as the selective probe for O₃ detection. For this purpose, a plastic cover on the surface of the drain was drilled to bare the drain surface, followed by its modification with nitrogen and sulfur-functionalized SWCNTs by chemical vapor deposition (CVD) process. The CVD-synthesized SWCNTs were then electrodeposited with FeOOH nanostructures. According to the figures of merit, the fabricated sensor gave a linear output from 20 to 450 parts per billion (ppb). Detection limit was also 4.1?ppb. Relative standard deviation (RSD) for seven replicate analyses was 3.61%. Based on 90% of maximum response (t₉₀), the response time was ～1.5?min. Calibration sensitivity was measured to 1.3?mV/ppb. No interference was observed, when introducing at least 500 folds of interferences of gaseous species such as H₂O, HCl, H₂S, O₂, H₂, CO, CO₂, NO₂, SO₂, Cl₂, C₂H₂, CH₄ and volatile organic compounds (VOCs) to 250?ppb of O₃ solution. Reliability of the sensor was also evaluated via determination of O₃ in different air samples.     

d-Glucosamine as an efficient and green additive for palladium-catalyzed Heck reaction

The Heck coupling of haloarenes with various alkenes was successfully performed in the presence of 0.5 mole % Pd(OAc)₂ and 1.0 mole % d-glucosamine as an additive with K₂CO₃ as the optimal base in a mixture of H₂O/iPrOH (φ _r = 2: 1) as the reaction solvent at 80°C after 6 h. d-Glucosamine was found to be an inexpensive, air-stable, easy to available, and efficient additive in palladium-catalyzed Heck reactions of aryl iodides (67–95 % conversion) and bromides (38–72 % conversion).     

Complexation ability of kryptofix 22DD with lanthanum (III) cation in some binary mixed non-aqueous solvents

The complex formation between lanthanum (III) cation with kryptofix 22DD was studied in acetonitrile–dimethylformamide (AN–DMF), acetonitrile–methanol (AN–MeOH), acetonitrile–ethylacetate (AN–EtOAc) and acetonitrile–ethanol (AN–EtOH) binary solvent solutions at different temperatures by using conductometric method. The conductance data show that in all cases, the stoichiometry of the complex formed between the macrocyclic ligand and the metal cation is 1:1 [ML]. The stability order of (kryptofix 22DD.La)³⁺ complex in the studied binary solvent solutions at 25 °C was found to be: AN–EtOAc>AN–EtOH>AN–MeOH>AN–DMF and in the case of pure non-aqueous solvents at 25 °C was: EtOAc>EtOH>MeOH>AN>DMF. A non-linear behavior was observed for changes of logK_f of (kryptofix 22DD.La)³⁺ complex versus the composition of the binary mixed solvents, which was explained in terms of solvent–solvent interactions and also the preferential solvation of the species involved in the complexation reaction. The values of standard thermodynamic parameters (?H _c°, ?S _c°) for formation of (kryptofix 22DD.La)³⁺ complex were obtained from temperature dependence of the stability constant using the van’t Hoff plots.The results show that in most cases, the (kryptofix 22DD.La)³⁺ complex is enthalpy destabilized, but entropy stabilized and the values of these thermodynamic quantities for formation of the complex are quite sensitive to the nature and composition of the mixed solvents solution.