Conceptual density functional theory (chemical hardness h, electronic chemical potential µ, global and local electrophilicity index w and wk, Fukui function f+k) is used to predict reactivity, stereo- and regioselectivity of the Diels-Alder (DA) reaction between 2-nitropyrrole and its N-tosylated derivative with Danishefsky's diene to yield 5-hydroxyindoles. In fact, the indexes are not useful for hetero-DA due to the fact that they give very high values at nitrogen or oxygen atoms of the nitro substituent. A detailed mechanistic study of various possible reaction channels is done by DFT [B3LYP/6-31G(d)] calculations. Solvent effects (benzene) are taken into account by the CPCM bulk solvation model. In principle, the nitropyrrole can either act as diene involving the nitro group (hetero-Diels-Alder reaction, HAD) or alternatively as alkene in a "normal" Diels-Alder reaction. While in several reactions of nitroalkenes the dihydrooxazine N-oxides could be observed (i.e. the products of nitroalkenes acting as heterodiene), under the experimental conditions used, N-tosyl-2-nitropyrrole yields solely the aromatic alcohol. This product can be formed either directly by Diels-Alder reaction of the nitropyrrole acting as alkene or by rearrangement of the dihydrooxazine N-oxides. The primary cycloadduct with the nitropyrrole acting as alkene is found to be unstable reacting further by extrusion of nitrous acid to 5-hydroxyindole. Any of the cycloadducts (DA or HDA) could in principle give the ArOH by HNO2 extrusion. Finally, the results are compared with those obtained for the analogous furans, thiophenes, and selenophenes.

Organotin(IV) carboxylates have expected much attention, owing to the enormous variety ofinteresting structural topologies and theirecological and biological chemistry activity.The ecological and biological chemistry of organotin(IV) carboxylates have been the subjects ofinterest for some time due to their increasingly extensive use inindustry and agriculture.thebiochemical activity of organotin carboxylates is influenced significantly by the structure of themolecule and the coordination number of the tin atoms. One types of diorganotin(IV) complexC53H57NO8Sn2was prepared by reactions of triphenyltin chloride with triethylamine andterimesicacid by ratio of 1:3:3.The complex is characterized by IR and NMR (1H, 13C, 119Sn)spectroscopies and X-ray single crystal diffraction.This copound crystallizes in the monoclinicsystem, space group P21/C with Z= 4.The unit cell dimensions for complex is : a =15.157(3) Å ,b = 20.802(4) Å and c = 15.719(3) Å.Spectroscopic data:IR (KBr, cm-1): 3296(s), 3064(s), 2678(s), 1622(s), 1429(s), 449(m)1H-NMR (DMSO-d6, ppm) δH: 1.06(t, 9H, CH3, J= 7), 2.82(q, 6H, CH2, J=7), 3.17 (s, 3H, CH3),7.34-7.87 (m, 30H, C6H5), 8.39(s, 3H)13C-NMR (DMSO-d6, ppm) δC: 9.4, 45.3, 48.6, 127.6, 128.1, 128.5, 132.4, 135.8, 136.2, 136.5,143.9, 168.4119Sn-NMR (DMSO-d6, ppm) δSn: 257.47

Pyrazinamide (PZA) is one of the most important molecules in the world. It is counted among the first-line antituberculotic drugs together with rifampicin, isoniazide, ethambutol or streptomycine. Using it as anti-tubercular agent it can shorten the time needed for treatment by two thirds and acts as sterilising drug. On the other hand, due to its small molecule and unique chemical properties, that makes this compound very suitable for structural modifications, new ways of use have appeared, such as antiviral, herbicidal, antibacterial, antineoplastic activities.There was prepared a series of 3-chloropyrazine-2-carboxamide, which is a derivative of PZA, and was treated with a group of aliphatic, alicyclic amines and saturated heterocycles containing nitrogen. All the final compounds were prepared using microwave reactor with focused field according to the experimentally set conditions. This approach was chosen according to higher yields, shorter reaction times and better conversion.Every product of this type of aminodehalogenation reaction was characterized chemically by melting point, 1H, 13C NMR and IR spectra, elemental analysis and lipophilicity (calculated and experimentally set). In vitro biological screenings followed.Antimycobacterial evaluation has been made against 4 mycobacterial strains (M. tuberculosis, M. kansasii and 2 strains of M. avium) and isoniazide has been used as a standard. Next screening has been focused on antibacterial and antifungal tests against 8 bacterial and 8 fungal stems. There have been used 5 antibiotics (neomycin, bacitracin, penicillin G, ciprofloxacin, phenoxymethylpenicillin) and 4 antimycotics (amphotericin B, voriconazole, nystatin, fluconazole) as standards. Minimal inhibition concentration has been set as 90% inhibition resp. 50% inhibition of control. The last evaluation has been focused on testing of herbicidal activity of these new compounds. The main principle of this measurement has been the inhibition of photosynthetic electron transport in chloroplasts that have been taken from spinach (Spinacea oleracea). The Hill reaction has been used together with DCMU (Diurone®) as standard. Inhibition concentration IC₅₀ has been recorded and the determination of site of action in photosynthetic apparatus (PA) of studied compounds has been performed using an artificial electron donor 1,5-diphenylcarbazide. Fluorescence measurements have been also used for monitoring the interaction of PZA analogues with amino acids residues present in PA.The results showed some antifungal activities but it was not enough to predict any structure-activity relationships. On the contrary, there was found a conspicuous relationship between lipophilicity and herbicidal activity in the aliphatic amines group.

Aluminium sulfate has mild acidity, yet the acidity of aluminium sulfate is not taken advantage of in organic synthesis. Here, we utilized aluminium sulfate for the first time in a multicomponent reaction for the synthesis of 1,4-dihydropyridine. A four-component one-pot synthesis of 1,4-dihydropyridine was carried out by condensing aromatic aldehyde, 2equivalent of ethyl acetoacetate, and ammonium acetate using a catalytic amount of aluminium sulfate (10%) refluxed in ethanol. The present protocol using aluminium sulfate a mild solid catalyst has several merits, such as low cost, high yield, and shorter reaction time, with no byproducts.

1,2,3-Triazole derivatives have received a great deal of attention because of their wide range of applications and biological activities such as anti-HIV and antimicrobial agents. The most popular method for the construction of 1,2,3-triazole frameworks is the 1,3-dipolar Huisgen cycloaddition reaction of azides with alkynes. However, a mixture of the 1,4- and 1,5-regioisomers may result, and efforts have been made to selectively gain one of the regioisomers. Huisgen reaction using amine or alcohol as one of the reactants to afford nitrogen and oxygen containing 1,2,3-triazoles have been already reported, but in the case of sulfur containing triazoles, it is desirable to develop a new, convenient and regiocontrolled synthetic approach. In this work, we have presented a three component reaction of thiols, propargyl bromide and organic azides using copper iodide catalyst under aerobic conditions in water to afford the corresponding sulfur containing1,4-disubstituted-1,2,3-triazoles. Our method has the advantages of operational simplicity, mild reaction conditions, use of ambient temperature, no moisture or air sensitivity, 1,4-regioselectivity and simple reaction work-up.

The palladium-catalyzed coupling of aryl halides with aryl boronic acids (Suzuki-Miyaura coupling) or terminal alkynes (Sonogashira-Hagihara coupling) reactions have shown to have widespread applications in the synthesis of natural products, biologically active molecules, and materials science. Many catalytic systems have been developed for the Suzuki-Miyaura and Sonogashira-Hagihara cross-coupling reactions using different palladium catalysts such as Pd(PPh₃)₄, PdCl₂(PPh₃)₂, and PdCl₂(CH₃CN)₂. However, phosphine ligands used in these reactions are sensitive to air oxidation. Moreover, many palladium catalysts used in the Suzuki-Miyaura and Sonogashira-Hagihara reactions are homogeneous; these catalysts are impossible to be recovered. In recent years, great efforts have been devoted to the introduction and application of effective heterogeneous catalysts. Studies on the isolation, characterization and catalytic activities of functionalized carbon nanotubes (CNTs) have received particular attention during the last decade owing to their specific catalytic applications compared to homogeneous complexes. Schiff bases, which are an important class of ligands with extensive applications in different fields, also showed excellent catalytic activity when grafted on CNTs. In this work, we have presented a multi-walled carbon nanotubes anchored Pd(II)-Schiff base complex as a heterogeneous catalyst for Suzuki-Miyaura cross-coupling reactions and copper- and phosphorous-free Sonogashira-Hagihara cross-coupling reactions in aqueous media under aerobic condition. The catalyst was air-stable and could be recovered and reused for four consecutive runs in Suzuki-Miyaura reaction and three successive runs in Sonogashira-Hagihara reaction.

Two novel and environmentally benign organosulfonic acid-functionalized silica-coated magnetic nanoparticle catalysts 1a (Fe₃O₄@SiO₂@Me&Et-PhSO₃H) and 1b (Fe₃O₄@SiO₂@Et-PhSO₃H) have been prepared and their hydrophobicity and acidity were investigated, and tested for the three-component Biginelli reaction of benzaldehyde, methylacetoacetate, and urea under solvent-free conditions. 1a, the solid catalyst which was more hydrophobic, showed higher catalytic activity and was characterized extensively by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analysis, H₂O-sorption analysis; thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM) and acid/base titration. This catalyst was used in the reactions of a series of aldehydes, β-keto esters, and urea/thiourea. The catalyst was easily separated by an external magnet and the recovered catalyst was reused in four cycles without significant loss of activity. This green and reusable catalyst accompanied by simple experimental procedure and product isolation could be considered as an alternative protocol which will hopefully develop a clean and eco-friendly strategy for the synthesis of 3,4-dihydropyrimidin-2-ones/thiones (DHPMs) derivatives.

Palladium-catalyzed cross-coupling reaction between aryl halides and terminal acetylenes (commonly referred to as the Mizoroki-Heck reaction) is a highly versatile, powerful and popular tool for the synthesis of variously substituted olefins, dienes and precursors to conjugated polymers. This reaction has also been utilized for the preparation of natural products,and pharmaceuticals. The traditional Mizoroki-Heck reaction is typically performed with 1-5 mol% of a palladium catalyst along with a phosphine or phosphorusligands in the presence of a suitable base. However, phosphine ligands are toxic, expensive, unrecoverable, and unstable at high temperatures; thus the development of a phosphine-free palladium catalyst is a topic of enormous interest. Moreover, the Mizoroki-Heck reaction still show some limitations, especially in relation to the use of certain reagents. In particular, a major restriction of palladium-catalyzed coupling processes has been the poor reactivity of cheaper and readily available aryl chlorides and aryl bromides in comparison with more active aryl iodides. Therefore, the search for efficient catalysts for the cross-coupling of olefins with deactivated aryl bromide and towards activated aryl chloride is under progress. Herein, we present a Pd(II) catalyst system based on a commercially available diazacrown ether or cryptand-22, PdCl₂-C22, that is very active homogeneous catalyst under aerobic conditions. This catalytic system is efficiently used for the Mizoroki-Heck cross-coupling reactions of aryl iodides, bromides as well as chlorides with various olefins. The remarkable chelating effect of this N- and O-containing ligand and its flexibility assists in stabilizing the reactive palladium intermediates, and suppresses the Pd black formation even at high temperature under air.

The field of fluorescent chemosensors has grown in recent years due to their importance in applications such as in material sciences, biomedical, analytical chemistry and environmental sciences. Following our research interests that include the synthesis and application of fluorimetric chemosensors for anions and cations based on heterocycles and amino acids, a new imidazo-benzocrown ether functionalised amino acid 3 was synthesized in 70% yield by condensation of functionalised phenylalanine 1 with 4-amino-5-nitrobenzo-15-crown-5-ether 2 in the presence of Na₂S₂O₄ in DMSO. Compound 3 was studied by fluorescence spectroscopy in the presence of increasing amount of metal ions such as Ca²⁺, Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe²⁺, Fe³⁺, Hg²⁺, Na⁺, Ni²⁺, Pd²⁺ and Zn²⁺. The metal cation sensing properties displayed by 3 showed that it is a promising candidate for sensory applications.

Cyclopropanation reactions involving a 1,4-addition to an electrophilic alkene followed by a cyclization are known as Michael initiated ring closure (MIRC) reactions. In recent years catalytic MIRC processes have attracted great interest for  the asymmetric construction of cyclopropanes. With the aim of expanding our previous studies on the synthesis of densely functionalized cyclopropanes, we now report preliminary results of investigations concerning novel cyclopropanations of vinyl selenones with dinucleophilic C1 synthons. The initially formed Michael adducts, after a proton transfer, can cyclize through an intramolecular nucleophilic substitution by taking advantage of the excellent leaving group ability of the phenylselenonyl group. Encouraging results were obtained from organocatalytic reactions with unsubstituted cyanoacetates, a bifunctional cinchona alkaloid-based organocatalyst and a base additive. Cyclopropanes bearing adjacent tertiary and quaternary stereocentres were generated in good yield, high diastereoselectivity and moderate enantioselectivity.Dedicated to Professor Lorenzo Testaferri on the occasion of his retirement.