A novel and efficient method has been developed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazole derivatives using (N-isocyanimino)triphenylphosphorane, a secondary amine, a carboxylic acid, and an aromatic aldehyde in CH(2)Cl(2) at ambient temperature in high yields without using any catalyst or activation. The procedure provides an alternative method to the synthesis of fully substituted 1,3,4-oxadiazole derivatives.

Graphene-based materials are revealing the leading edge of advanced technology for their exceptional physical and chemical properties. Chemical manipulation on graphene surface to tailor its unique properties and modify atomic structures is being actively pursued. Therefore, the discovery of robust and general protocols to anchor active functionality on graphene basal plane is still of great interest. Multicomponent reactions promise an enormous level of interest due to addressing both diversity and complexity in combinatorial synthesis, in which more than two starting compounds react to form a product derived from entire inputs. In this article, we present the first covalent functionalization route beginning with carboxylated-graphene oxide through Ugi four-component assembly process (Ugi 4-CAP), in which amine, aldehyde, isocyanide, and acid components come together in a one-pot reaction to generate hydrophobic-, hydrophilic-, or amiphiphilic multifunctionalized graphene composites. Investigation on the covalent immobilization and biocatalytic activity of Bacillus thermocatenulatus lipase (BTL) on graphene surface showed the efficiency and competency of Ugi 4-CAP. The success of the multicomponent-coupling approach was confirmed by atomic force microscopy, Raman spectroscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy, 1H NMR, energy-dispersive X-ray spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy.

An ecofriendly inorganic–organic hybrid and novel Schiff base complex of copper coated on epoxy-modified Fe3O4@SiO2 MNPs was successfully designed and prepared from readily available chemicals. In this method, a Schiff base complex as a linker is utilized to protect copper nanoparticles to the core–shell Fe3O4 exterior without agglomeration. The resulted Schiff base complex of copper coated on epoxy-modified Fe3O4@SiO2 MNPs was characterized and confirmed via different analyses such as FT-IR, TGA, XRD, VSM, FE-SEM, TEM, ICP, EDX, and BET. The novel catalyst was examined for the synthesis of various chromene-annulated heterocycles through the one-pot three component reaction of aromatic aldehydes, various phenols (2-hydroxynaphthalene-1,4-dione/resorcinol/β-naphthol), and malononitrile in ethanol at reflux conditions. This method includes important aspects like no usage of column chromatography, very short reaction times, simplicity of product isolation using ethanol, excellent yields, simple procedures, and magnetic recoverability of the catalyst. All in all, our method makes a novel and significant advancement in the synthesis of various chromene-annulated heterocycles.

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An efficient and heterogeneous novel magnetic silica-coated picolylaminecopper complex [Fe3O4@SiO2@GP/Picolylamine-Cu­(II)] was synthesized, characterized, and employed as a magnetically recoverable nanocatalyst in Biginelli condensation for the preparation of biologically active 3,4-dihydropyrimidinones. Fe3O4@SiO2@GP/Picolylamine-Cu­(II) was synthesized easily using chemical attachment of the picolylaminecompound on Fe3O4@SiO2@GP, followed by treatment with copper salt in ethanol under reflux conditions. Fe3O4@SiO2@GP/Picolylamine-Cu­(II) was affirmed by various analyses such as Fourier transform infrared, thermogravimetric analysis, X-ray diffraction, vibrating-sample magnetometry, field-emission scanning electron microscopy, transmission electron microscopy, DLS, inductively coupled plasma, energy-dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller. The resulting catalyst system was successfully used in the Biginelli reaction through a variety of compounds such as aromatic aldehyde, urea, and ethyl acetoacetate under solvent-free conditions or ethylene glycol at 80 °C and yielded the desired products with high conversions with powerful reusability. The current approach was convenient and clean, and only 0.01 g of the catalyst could be used to perform the reaction. The easy work-up procedure, gram-scale synthesis, usage of nontoxic solvent, improved yield, short reaction times, and high durability of the catalyst are several remarkable advantages of the current approach. Also, the Fe3O4@SiO2@GP/Picolylamine-Cu­(II) nanocatalyst could be recycled by an external magnet for eight runs with only a significant loss in the product yields.

An effective heterogeneous nanocatalyst was successfully designed by immobilization of tungstate ions (WO 4 2− ) onto the modified surface of carbon quantum dots (CQDs) with the 1-aminopropyl-3-methyl-imidazolium chloride ([APMim][Cl]). In this work, for the first time, the synthesized CQDs@IL/Cl − , via a facile one-step hydrothermal method, was used as an adsorbent and stabilizing support for tungstate ions. Characterization of the synthesized nanoparticles (NPs) by various physicochemical techniques illustrated that tungstate ions have been immobilized on the surface of IL-modified CQDs. With this novel nanocatalyst, a variety of primary, secondary alcohols, and other alcohol substrates have been efficiently oxidized to their corresponding aldehydes and ketones in yields of ≥88% with high selectivity (100%). In the presence of CQDs@IL/WO 4 2− as a recyclable nanocatalyst, all alcohol substrates without overoxidation to carboxylic acid were oxidized within 2 h, under a temperature of 70 °C with H 2 O 2 as the oxidant. The above catalyst can be readily recycled using a simple extraction and reused consecutive runs under the described reaction conditions without a considerable decrease in the activity and selectivity. In conclusion, this Article offers a novel application for CQD chemistry.

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Achieving green and sustainable chemical processes by replacing organic solvents with water has always been one of the green chemistry goals and a challenging topic for chemists. However, the poor solubility of organic materials is a major limitation to achieving this goal, especially in alcohol oxidation. In this contribution, the development and design of amphiphilic catalysts via abundant, safe, cheaper, and more biocompatible sources have received notable attention. To this purpose, herein, our group successfully synthesized a new multifunctional amphiphilic carbon quantum dot (CQD) composed of 1-aminopropyl-3-methyl-imidazolium chloride ([APMim]­[Cl]), dodecylamine (DDA), and citric acid (CA) (denoted as CQDs@DDA-IL/Cl) using a one-pot hydrothermal route. The CQDs@DDA-IL/Cl was then utilized as an amphiphilic stabilizer for anchoring tungsten ions using an anion-exchange method (marked as CQDs@DDA-IL/W). The CQDs@DDA-IL/W as a reusable catalyst selectivity mediated the oxidation of alcoholic substrates with stoichiometric H2O2 in water solvent. The extraordinary performance of our catalyst was attributable to the coexistence of ionic liquid (IL) and DDA upon the surface of the CQDs@DDA-IL/W, which plays a main duty in the hydrophobic/hydrophilic balance, and significantly increase the catalyst compatibility in the aqueous medium with the purpose of removing organic solvents. As a result, the great mass transfer occurs in the two-phase medium using this amphiphilic nanocatalyst without any phase transfer catalyst (PTC) or other additives. The 100% selectivity, excellent turnover number (TON) and turnover frequency (TOF), high yield, almost complete and fast conversion of alcohol to the desired aldehydes and ketones without more oxidation, and easy and no-trouble isolation of product and catalyst are outstanding features of this catalytic system.