A one-pot microwave-assisted synthesis of pyrido[2,3-d]pyrimidines

A high yield multicomponent reaction providing multifunctionalized pyrido[2,3-d]pyrimidines with up to four diversity centers in a one-pot microwave-assisted cyclocondensation of alpha,beta-unsaturated esters, amidine systems and malononitrile (or ethyl cyanoacetate) is described.     

Facile and rapid one-pot microwave-assisted synthesis of Pd-Ni magnetic nanoalloys confined in mesoporous carbons

An easy and rapid one-pot microwave-assisted soft-template synthesis method for the preparation of Pd-Ni nanoalloys confined in mesoporous carbon is reported. This approach allows the formation of mesoporous carbon and the growth of the particles at the same time, under short microwave irradiation (4 h) compared to the several days spent for the classical approach. In addition, the synthesis steps are diminished and no thermopolymerization step or reduction treatment being required. The influence of the Pd-Ni composition on the particle size and on the carbon characteristics was investigated. Pd-Ni solid solutions in the whole composition range could be obtained, and the metallic composition proved to have an important effect on the nanoparticle size but low influence on carbon textural properties. Small and uniformly distributed nanoparticles were confined in mesoporous carbon with uniform pore size distribution, and dependence between the nanoparticle size and the nanoalloy composition was observed, i.e., increase of the particle size with increasing the Ni content (from 5 to 14 nm). The magnetic properties of the materials showed a strong nanoparticle size and/or composition effect. The blocking temperature of Pd-Ni nanoalloys increases with the increase of Ni amount and therefore of particle size. The magnetization values are smaller than the bulk counterpart particularly for the Ni-rich compositions due to the formed graphitic shells surrounding the particles inducing a dead magnetic layer.

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Graphical abstract PdNi nanoalloys confined in mesoporous carbon exhibiting magnetic properties dependent on thealloys composition and size were synthesized by a fast microwave approach

     

A novel and facile synthesis of N-cyclohexyl-benzofurans by one-pot three-component reaction

Abstract  

A simple and efficient synthesis of N-cyclohexyl-benzofuran derivatives was achieved via a one-pot three-component reaction of cyclohexylisocyanide, an aromatic aldehydes, and phenols in DMF for 10 h with good yields.     

Tribological behaviors of dialkyldithiophosphate-encapsulated Ni nanoparticles prepared by microwave-assisted reaction

We applied the microwave-assisted heating method to prepare the pyridine dialkyldithiophosphate-encapsulated Ni (Ni-DDP) nanoparticles. The surface-encapsulated Ni particles were characterized by Fourier transform infrared spectrometer, thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. Their tribological behavior in lubricate base oil was investigated on four-ball machines. The results show that uniform Ni-DDP nanoparticles about 12 nm can be obtained using microwave heating device and also they exhibit good tribological behaviors dispersed in liquid paraffin.     

Structural and optical properties of ZnO nanopowder prepared by microwave-assisted synthesis

We report the characterization of nano-size zinc oxide (ZnO) powder synthesized via microwave-assisted heating of Zn(CH₃COO)₂·2H₂O and NaHCO₃ solution with deionized water (DI water) as the solvent. The as-synthesized ZnO powder was calcined at temperatures from 400 to 800 °C for 8 h. The X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) spectra revealed pure wurtzite structure for the ZnO nanopowder (NP) calcined at 800 °C. Scanning electron microscopy (SEM) images showed increasing size ZnO NP with uniform size distribution with increase in calcination temperature. Significant UV emission at about 373 nm has been observed in the photoluminescence (PL) spectra of the as-synthesized and calcined ZnO NP. Our results showed enhanced PL intensity with a reduced full-width at half-maximum (FWHM) for ZnO NP synthesized at higher calcination temperature.     

Hydrothermal and microwave-assisted synthesis of nanocrystalline ZnO photocatalysts

Novel methods of highly dispersed ZnO powder synthesis based on microwave heating of salt mixtures as well as low temperature microwave-assisted hydrothermal treatment of zinc hydroxide were developed. It was shown that the obtained powders possess high photocatalytic activity in a model reaction of methyl orange photodegradation.     

A novel class of extended pi-conjugated systems: one-pot synthesis of bis-3-aminoimidazo[1,2-a]pyridines, pyrimidines and pyrazines

Bis-3-aminoimidazo[1, 2-a] pyridines, pyrimidines and pyrazines as extended pi-conjugated systems were synthesized for the first time by a novel pseudo five-component condensation of 2-aminopyridine pyrimidines and pyrazines derivatives with terephthalaldehyde or isophthalaldehyde and isocyanides in the presence of p-toluenesulfonic acid in methanol.     

Regioselective sonochemical synthesis of genistein derivatives

Differential functionalization of the phenolic groups in genistein was carried out in excellent yields under ultrasonic irradiation. The isoflavone ring had proved to be unstable under stirring at 60 degrees C and phenyl benzyl ketone was unexpectedly isolated instead of the genistein derivative.     

Combining click-multicomponent reaction: one-pot synthesis of triazolyl methoxy-phenyl indazolo[2,1-b]phthalazine-trione derivatives

[(1,2,3-Triazol-4-yl)methoxy-phenyl]-2H-indazolo[2,1-b]phthalazine-trione derivatives were synthesized in a simple and efficient method from the one-pot four-component condensation reaction of phthalhydrazide, aromatic propargyloxy aldehydes, active methylene compounds (dimedone and 1,3-cyclohexanedione), and azides in the presence of Cu(OAc)(2)/sodium ascorbate and p-toluenesulfonic acid as catalysts in good to excellent yields.     

Eco-efficient ultrasonic responsive synthesis of pyrimidines/pyridines

Using ultrasound irradiation, two simple one-pot multicomponent methods are described for syntheses of highly functionalized pyrimidine/pyridine derivatives in excellent yields in the presence of NaOH at room temperature. While one route involved aromatic aldehyde, thiourea and acetoacetanilide, the other employed aromatic aldehyde, malononitrile and benzyl mercaptane or EtOH. These approaches afford several advantages over former and contemporary reaction methodologies in terms of operational simplicity, simple work-up procedure, higher yield, short reaction time and environment friendly protocols.     

A mild and efficient one-pot synthesis of \upbeta -amino carbonyl compounds via Mannich reaction under ambient temperature condition

We have developed an efficient protocol for the synthesis of $\upbeta $ -amino carbonyl compounds using phenylboronic acid as effective and eco-friendly catalyst via one-pot three-component Mannich reaction. Excellent yields, mild reaction condition, and simple experimental work-up procedure are some of the advantages of this method, which makes it a useful protocol for the synthesis of $\upbeta $ -amino carbonyl compounds.     

Ultrasound assisted one-pot, three-components synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines: A new access via phenylsulfone synthon

A simple, facile, efficient and three-components procedure for the synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines utilizing phenylsulfone synthon, under ultrasonic irradiation was developed.     

Simultaneous sonication assistance for the synthesis of tetrahydropyridines and its efficient catalyst ZrP2O7 nanoparticles

In this research, a general synthetic method for the synthesis of tetrahydropyridines were developed using ZrP₂O₇ nanoparticles under ultrasonic irradiations. Firstly by a simple and green process, nano zirconium pyrophosphate was prepared via sonication. Subsequently, this nanoparticle was used as an efficient catalyst for the synthesis of highly functionalized tetrahydropyridines via five-component reaction of aromatic aldehyde, amine and ethyl acetoacetate in ethanol under ultrasound irradiation. The present approach offers several advantages such as high yields, environmentally benign, simple work-up, excellent yield of products, short reaction times as well as recoverability and reusability of the catalyst.     

Regioselective formation of 1,2,4-triazoles by the reaction of amidrazones in the presence of diethyl azodicarboxylate and catalyzed by triethylamine

Molecular Diversity - A general method for the synthesis of 1,3,5-trisubstituted 1,2,4-triazoles has been developed from reaction of amidrazones with ethyl azodicarboxylate and triethylamine...     

First ultrasound-mediated one-pot synthesis of N-substituted amides

Ultrasound irradiation, an efficient and innocuous technique of reagent activation for synthesizing organic compounds, has been applied with success to transform seven carboxylic acids to fourteen secondary amides in good to excellent yields. The reaction has worked well either with aryl or alkyl carboxylic acids as well as with aromatic or aliphatic amines. This methodology is expeditious and reliable for preparing secondary carboxamides which in many cases are embedded in the C-5 side-chain of 1,2,4-oxadiazoles (14, 15, 17–27). The elemental analyses of new compounds (19–27) in conjunction with the spectral data of all synthesized amides gave an idea about their structures, while the crystallographic data of one of the compounds (26) supplied information concerning the configurational behavior of the amidic part and also the conformational aspect of the entire molecule in the crystalline state.     

Divergent reaction pathways for one-pot,three-component synthesis of novel 4H-pyrano[3,2-h]quinolines under ultrasound irradiation

The present paper deal with the multi-component condensation of 8-hydroxy quinoline, aromatic aldehydes, and sulfone derivatives catalyzed by p-toluenesulfonic acid for the synthesis of a series of 4H-pyrano[3,2-h]quinoline derivatives in ethanol under ultrasonic irradiations. We provide a series of quinoline derivatives containing sulfone moiety interesting for biological screening tests. The reactions were carried out under both conventional and ultrasonic irradiation conditions. In general, improvement in rates and yields were observed when reactions were carried out under sonication compared with classical silent conditions. Also, also, sonochemical reaction give different reaction pathway other than silent reaction. These remarkable effects appeared in sonicated reactions can be reasonably interpreted in terms of acoustic cavitation phenomenon. Structures of the products were established on analytical and spectral data.     

Rapid microwave-assisted synthesis and electrochemical characterization of gold/carbon nanotube composites

Hybrid nanostructures composed of gold nanoparticles (NPs) and carbon nanotubes (CNTs) have been prepared by a microwave-assisted method in the mixed solvents of oleylamine and oleic. The morphology, structure and composition of as-obtained Au/CNT composites are characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD). The composites show characteristic plasmon absorption of Au NPs in the Ultraviolet–visual spectrum. Fourier transform infrared spectrum shows the successful introduction of functional groups on the surface of CNTs, which are crucial factors to assist the nucleation in situ of Au NPs on the surface of CNTs. Electrochemical measurements show the enhancement electrochemical response for the gold electrode modified with Au/CNT composites.