Asymmetric cross-aldol reaction of isatin and ketones catalyzed by crude earthworm extract as efficient biocatalyst

ABSTRACT

The asymmetric cross-aldol reaction of simple ketones (acetone, cyclohexanone) with isatin derivatives in the presence of crude extract from earthworms as green and effective biocatalyst proceeds easily in MeCN/H₂O (1:1) as solvent to afford 3-hydroxy-2-oxindoles derivatives. Ten compounds were synthesized in high yields (62–88%) and moderate ee (29–42%). Structure of the synthesized compounds has been characterized on the basis of NMR spectra and CHN analysis. The ee of the obtained compounds was determined by chiral phase HPLC analysis.     

Kinetic Isotope Effect as a Tool To Investigate the Oxygen Reduction Reaction on Pt-based Electrocatalysts – Part II: Effect of Platinum Dispersion

We investigated the oxygen reduction reaction (ORR) mechanism on Pt nanoparticles (NPs) dispersed on several carbon blacks with various physicochemical properties (i. e. specific surface ranging from 80 to 900 m² g⁻¹, different graphitization degree, etc.). Using the kinetic isotope effect (KIE) along with various electrochemical characterizations, we determined that the rate determining step (RDS) of the ORR is a proton-independent step when the density of Pt NPs on the surface of the carbon support is high. Upon decrease of the density of Pt NPs on the surface, the RDS of the ORR starts involving a proton, as denoted by an increase of the KIE >1. This underlined the critical role played by the carbon support in the oxygen reduction reaction electrocatalysis by Pt supported on high surface area carbon.     

Role of sodium decoration on the methane storage properties of BC3 nanosheet

First-principles calculations including dispersion correction are carried out to investigate pristine and Na-decorated graphene-like BC₃ (h-BC₃) for their application as methane storage materials. Structural optimization shows that the methane is physisorbed on the pristine sheet via van der Waals forces with adsorption energy of ?2.7 kcal/mol. It was found that unlike the pristine graphene, sodium decorated sheet can effectively interact with the CH₄ molecule, so that each metal atom bound on sheet may adsorb up to four CH₄. Furthermore, no bond dissociation was observed for the adsorption of CH₄ on Na-decorated h-BC₃, which means that decorated sheet can act as a storage device for methane safety storage. The results indicate that decoration of the Na atom on surface of sheet induces significant changes in electronic properties of the sheet and its E _g is unchanged after adsorption of CH₄ molecules. Theoretical methane storage capacity of Na-decorated BC₃ nanosheet could approach 18.1 wt%.     

Mercuric chloride adsorption on sulfur-containing BC2N nanotube: toward HSAB concept

Electronic sensitivity of pristine and sulfur-containing BC₂N nanotubes to mercuric chloride (HgCl₂) molecule was investigated by utilizing density functional theory. It was found that HgCl₂ is weakly adsorbed on the tube, releasing energy of 6.4–8.1 kcal/mol, and electronic properties of the tube are not significantly changed. To overcome this problem, carbon atoms of the tube were substituted by sulfur atom. Of interest are sulfur derivative functional adsorbents because of their strong affinity toward mercury. This observation may be explained based on the Pearson’s hard–soft acid–base theory. It was demonstrated that the S-doped tube can not only strongly adsorb the HgCl₂ molecule, but also may effectively detect its presence due to drastic increment of the tube electrical conductivity.     

Synthesis of 2-(2-Fluorophenyl)-2-methylamino-Cyclohexanone as a New Ketamine Derivative

The main goal of this article is to the present research on the development of ketamine derivatives. The target molecule was a fluoroderivative of ketamine, for which a multistep synthesis has been reported. This novel ketamine derivative, 2-(2-fluorophenyl)-2-methylamino-cyclohexanone, has been called fluoroketamine by our research group. The starting fluorobenzonitrile was reacted with the appropriate Grignard reagent followed by the bromination reaction to obtain α-bromocyclopentyl-(2-fluorophenyl)-ketone. The reaction of the obtained ketone with methylamine at ?40 °C then resulted in the formation of α-hydroxycyclopentyl-(2-flourophenyl)-N-methylamine. Finally, the five-memberd ring cyclopentanol was expanded to the cyclohexylketone by a thermal rearrangement reaction. The HCl salt of the target molecule, which is soluble in water, was obtained by the acidification of the free fluoroketamine with HCl. Preliminary animal tests on mice have shown that the resulting fluoroketamine has some advantages over ketamine in terms of the effective dose and the recovery time.     

Design,synthesis and antibacterial activity evaluation of novel 2-(4-((1-aryl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)2-(2-oxoazetidin-1-yl)acetamide derivatives

In this paper, a novel series of 2-(4-((1-aryl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)2-(2-oxoazetidin-1-yl)acetamide derivatives are synthesized in two steps. The first step involved Ugi multicomponent reaction of β-alanine, o-(propargyl)benzaldehyde and isocyanide derivatives. The product of this step, underwent a click 1,3-dipolar cycloaddition reaction with benzyl azide derivatives. The 2-(4-((1-aryl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)2-(2-oxoazetidin-1-yl)acetamide product was characterized and their antibacterial activities were evaluated against various G-positive (Staphylococcus aureus and Bacillus subtilis) and G-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria, using minimal inhibition concentration. The compounds showed very good antimicrobial activity and a number of products have been more active than ciprofloxacin.     

A Simple Indirect Route for the Synthesis of N-Alkyl-4-imino-1,4-dihydro-2H-3,1-benzoxazin-2-ones

Summary. Novel N-alkyl-4-imino-1,4-dihydro-2H-3,1-benzoxazin-2-ones were synthesized in a single step by Baeyer–Villiger oxidation of N-alkyl-3-imino-2-indolinone derivatives in high yields. The structures of the products were determined by spectral data and by X-ray diffraction. Besides their novel structures, these compounds may have important biological activities and industrial applications.     

Synthesis,characterization and catalytic application of tributyl(carboxymethyl)phosphonium bromotrichloroferrate as a new magnetic ionic liquid for the preparation of 2,3-dihydroquinazolin-4(1H)-ones and 4H-pyrimidobenzothiazoles

Research on Chemical Intermediates - In this paper, tributyl(carboxymethyl)phosphonium bromotrichloroferrate as a new magnetic ionic liquid bearing acetic acid tags was synthesized and...     

Multi-component synthesis of highly substituted imidazoles catalyzed by nanorod vanadatesulfuric acid

Nanorod vanadatesulfuric acid (VSA NRs), as a recyclable and eco-benign catalyst, was used for one-pot synthesis of 2,4,5-trisubstituted imidazoles and 1,2,4,5-tetrasubstituted imidazoles using aldehydes, benzil, benzoin or 9,10-phenanthrenequinone and ammonium acetate or aniline under solvent-free conditions providing high to excellent yields. VSA is easily prepared by a simple reaction of chlorosulfonic acid and sodium metavanadate in high purity. As compared with the conventional procedures, the present protocol offers several advantages such as simplicity of procedure, short reaction time, high yields, easy workup, recoverability and reusability of the catalyst and simple purification of the products.     

An experimental study of the effects of Matricaria chamomilla extract on cutaneous burn wound healing in albino rats

Previous studies conducted on the anti-inflammatory, antimicrobial and antioxidant effects of Matricaria chamomilla (chamomile) extract led us to study the effect of topical chamomile extract on burn wound healing in albino rats. Thirty male albino rats (250-300 g) were randomly divided into three groups, as control, vehicle, and treatment. Second-degree burning was induced in 20% of whole surface area of animal body by placing the back of animal into boiling water for 8s. Animals of control group received no treatment. Animals of vehicle and treatment groups were treated topically by olive oil and extract dissolved in olive oil twice a day respectively from the first day of burn induction to complete wound healing. The percentage of wound healing was calculated weekly. The results showed that there was significant difference (p < 0.05) between vehicle and treatment groups. So we concluded that the chamomile extract in the form of rubbing oil had a good potential for acceleration of burn wound healing in rats.