Visible light irradiation promoted catalyst-free and solvent-free synthesis of pyrano[2,3-d]pyrimidine scaffolds at room temperature

A catalyst-free and solvent-free synthetic route for convenient one-pot synthesizing pyrano[2,3-d] pyrimidine scaffolds through Knoevenagel-Michael cyclocondensation is reported using visible light irradiation as a green promoter at room temperature based on green chemistry principles. Completing the reactions takes thoroughly less time while obtaining the products in outstanding yields. This green method includes the application of non-hazardous reaction circumstances, direct work-up without column chromatographic separation, catalyst-free, solvent-free, cost effective, simple synthesis, one-pot procedure, and high atom-economy.     

Solvent-free and catalyst-free method for the synthesis of 2,4,5-triarylimidazoles under microwave irradiation

A facile procedure for the synthesis of 2,4,5-triarylimidazoles is being reported starting from benzil, aromatic aldehyde and ammonium acetate. The reactions were carried out with catalyst-free, solvent-free and under microwave irradiation conditions in high yield (80–99%) with short time (3–5 min) and environmental benign, as well as convenient operation. The structures of the compounds have been confirmed on the basis of their IR, ¹H NMR, and/or ¹³C NMR, MS, and elemental analyzer.     

An ultrasound-promoted green approach for the N-formylation of amines under solvent- and catalyst-free conditions at room temperature

A new environmentally benign, convenient, and facile methodology for the N-formylation of amines is reported using ultrasound irradiation under solvent- and catalyst-free conditions at room temperature. Compared with conventional methods, the main advantages of the present procedure are milder, cleaner and greener conditions, shorter reaction time, higher purity and yields, simpler work-up, and lower generation of waste or pollutions.     

One-pot synthesis of oxazoles using isocyanide surrogates

We wish to present herein a simple one-pot synthesis of 2,5-disubstituted oxazoles, starting from benzyl halides and acyl chlorides. The in situ formation of isocyanides, followed by the addition of an acyl chloride in the presence of a base leads to the desired oxazoles in good yields.     

An efficient catalyst-free regio- and stereoselective ring-opening of epoxides with phenoxides using polyethylene glycol as the reaction medium

A catalyst-free regio- and stereoselective ring-opening of epoxides with phenoxides has been carried out efficiently using polyethylene glycol as the reaction medium to form the corresponding β-aryloxyalcohols in high yields at room temperature.     

LIC-KOR promoted formation of conjugated dienes as useful building blocks for palladium-catalyzed syntheses

It is demonstrated that α,β-unsaturated acetals can be considered a synthetic tool for transforming carbonyl derivatives into cheap and easily accessible starting materials for the construction of various and more complex structures. The lithium-potassium mixed superbase LIC-KOR induces a conjugate elimination reaction that converts α,β-unsaturated acetals into 1E-1-alkoxybuta-1,3-dienes. These derivatives can be readily metalated in situ and functionalized by reaction with electrophiles. The results can be grouped in two sections: (1) the palladium-catalyzed cross-coupling reaction between alkoxydienylboronates and tetralone- or isochromanone-derived vinyl triflates; (2) the regio- and stereoselective cross coupling reaction with aryl derivatives in the presence of a palladium catalyst (Heck conditions).     

微波辐射促进N－烷基化邻硝基苯胺的合成

报道了微波辐射促进芳香氯与胺衍生物的亲核取代反应，应用这一新的有效合 成方法能以50％－99％的产率快速合成N－烷基化邻硝基苯胺构建单元。     

Microwave and ultrasound promoted synthesis of substituted new arylhydrazono pyridinones

A variety of arylhydrazonopyridinones 6a,b were prepared via heating cyanoacetamide derivative with ethyl acetoacetate in the absence of solvent under reflux conventionally or ultrasound irradiation or in a microwave oven then coupling with heteroaromatic diazonium salts. Several attempts were made to synthesize corresponding aminothienopyridinones 7a,b from 6a,b. Also, attempts to add electron poor olefins to 6a,b have failed and only arylhydrazonopyridinones recovered.     

Cyclodextrin-based thiacavitands as building blocks for the construction of metallo-nanotubes

Two new cyclodextrin-based ligands with dual exo/endo binding domains were synthesised in high yields by reacting dimesylated or tetramesylated α-CD derivatives with sodium sulfide in either dimethylsulfoxyde or acetone/18-crown-6. The capping of adjacent glucose units was shown to be strongly favoured in both cases. Depending on the nature of the metal precursor being used, one of the synthesised thiacavitands forms either rigid nanotubular dimers or chelate complexes having receptor properties upon metal complexation.     

Ultrasound enhanced synthesis of 1,5-benzodiazepinic heterocyclic rings

1,5-Benzodiazepines are synthesized by a reaction of o-phenylenediamines with a diketone or ketones series by ultrasound irradiation in presence of APTS. The condensation occurred in a mild condition with good to excellent yields.     

Catalyst-free and solvent-free method for the synthesis of quinoxalines under microwave irradiation

A facile procedure for the synthesis.of quinoxalines is being reported starting from benzil and 1,2-diaminobenzene. Thereactions were carried out catalyst-free, solvent-free and under microwave irradiation conditions in high yield (84-98%) with short time (3-6 rain) and environmental benign, as well as convenient operation. The structures of all the compounds have been confirmed on the basis of their IR, 1H NMR, and/or 13C NMR, mass spectral data.     

Octahedral niobium chloride clusters as building blocks of templated prussian blue framework analogues

The preparation, structure, and magnetic properties of the first three-dimensional framework containing octahedral niobium cyanochloride clusters as building units are reported. Reactions of aqueous solutions of (Me(4)N)(2)K(2)[Nb(6)Cl(12)(CN)(6)] (2) with aqueous solutions of MnCl(2) result in the precipitation of the compound (Me(4)N)(2)[MnNb(6)Cl(12)(CN)(6)] (3). The structure of 3 was determined from single-crystal X-ray diffraction study (crystal data: cubic, Fm3macrom(No. 225), a = 15.513(4) A, V = 3733.2(12) A(3), Z = 4). Its 3D framework is based on edge-bridged [Nb(6)Cl(12)](2+) clusters and Mn(2+) ions bridged by cyanide ligands to form a cfc lattice [MnNb(6)Cl(12)(CN)(6)](2)(-) in which all tetrahedral sites are occupied by the cations (Me(4)N)(+) which act as charge compensating template. The structure of 3 can be considered as an expansion of the Prussian blue framework in which [Fe(CN)(6)](4)(-) is replaced by the cluster [Nb(6)Cl(12)(CN)(6)](4)(-). Magnetic susceptibility measurements indicate that Mn(2+) is present in a high spin d(5) configuration. No magnetic ordering is observed.     

Carbon dots as building blocks for the construction of functional nanocomposite materials

Journal of the Iranian Chemical Society - Carbon dots (CDs) are carbon-based quasi-spherical fluorescent nanoparticles with unique physical and chemical properties. Due to their complexity and...     

Ultrasound promoted direct synthesis of nano Cu-Zn-Al-ZSM-5 in acid medium

Nano Cu-Zn-Al-ZSM-5 was directly synthesized in HCl solutions with the promotion of ultrasound. XRD results show that the appropriate concentrations of HCl in the synthetic process were between 0.25 M and 1 M, and the optimal crystallization time and temperature were 28 h and 200°C, respectively. The ultrasound irradiation can significantly increase the crystallization of Cu-Zn-Al-ZSM-5 within 0.5 h. SEM photographs of Cu-Zn-Al-ZSM-5 zeolite showed the crystal size is about 50–60 nm. Results of ICP/AES show that the weight% of Cu in 101(Cu-Zn-Al-SOD) and 202(Cu-Zn-Al-ZSM-5) were 4.42% and 2.30%, respectively.     

Ionic liquid promoted selective debromination of α-bromoketones under microwave irradiation

The debromination of α-bromoketones with an easily accessible ionic liquid, 1-methyl-3-pentylimidazolium tetrafluoroborate, [pmIm]BF₄ under microwave irradiation has been investigated. By controlling the reaction time gem-α-dibromoketones are selectively debrominated to either monobromo or debromoketones. The α-monobromo- and α-monoiodoketones are dehalogenated while the corresponding chloroketones remain inert. The activated vic-bromoacetates are converted to the corresponding (E)-alkenes by the same procedure. These reactions do not require any organic solvent, any metal or any conventional reducing agent. The ionic liquid works here as catalyst as well as reaction medium and is recycled without any appreciable loss of its catalytic efficiency.     

Ring-size controllable metallamacrocycles as building blocks for the construction of microporous metal-organic frameworks

Presented here is a new strategy for the synthesis of metallamacrocycles (MC[n]) with different ring-size and guest selectivity via integrating a flexible trinuclear metal unit and a bridging organic ligand, and further body-centered cubic packing of these MCs results in the formation of three microporous MOFs for potential application in gas storage.     

Synthesis of aryl-hydrazones via ultrasound irradiation in aqueous medium

The synthesis of aryl-hydrazones from aromatic aldehydes/ketones and hydrazides (semicarbazide, thiosemicarbazide and aminoguanidine) is described using aqueous medium (acid conditions) under ultrasound irradiation with short reaction times (20-30 min), the reactions occurring at room temperature and giving rise to good to excellent yields of the products, along with the diastereoselectivities. The procedure is also simple and clean.     

Rigid chiral carbocyclic clefts as building blocks for the construction of new supramolecular hosts

The synthesis and resolution of two chiral carbocyclic cleft molecules containing carbonyl groups on the periphery of the cavity are reported. These compounds are reminiscent of Tröger's base but contain a smaller cleft and additional carbonyl (or alcohol) groups. X-ray crystal structures of the dibromo and dimethyl derivatives show that the dihedral angle between the two aromatic rings is 79° and 85° respectively. The dibromo derivative provides entry into new supramolecular hosts, via introduction of additional recognition groups into the cleft molecules.     

An efficient synthesis of ferrocenyl substituted 3-cyanopyridine derivatives under ultrasound irradiation

An efficient synthesis of 2-alkoxy-4-aryl-6-ferrocenyl-3-cyanopyridines via the condensation of ferrocenyl substituted chalcones with malononitrile in a freshly prepared sodium alkoxide solution under ultrasound irradiation was investigated. Especially noteworthy, the reaction of 1-ferrocenyl-3-(pyridin-2-yl)prop-2-ene-1-one with malononitrile afforded 2-alkoxy-4-pyridyl-6-ferrocenylpyridine, with the loss of CN group on the 3-position of pyridine ring was first observed.     

Design of new macromolecular architectures by using quasi-equivalent monodendrons as building blocks

Quasi-equivalent building blocks are chemically identical subunits which self-control their shape by switching between different conformational states. Classic biological examples are the flat-tapered and conical protein coats which jacket nucleic acids during the self-assembly of rod-like and icosahedral viruses, respectively. This paper advances the hypothesis that monodendrons can act as synthetic quasi-equivalent building blocks. The rational design of flat-tapered and cone shaped quasi-equivalent monodendrons and their use in the construction of three dimensional supramolecular and macromolecular rod-like and spherical systems demonstrates the above hypothesis. Mechanisms which interconvert the spherical systems into rod-like ones by using the same monodendron building blocks, thus demonstrating their quasi-equivalence, will be exemplified.