Nucleic acid analogues play a multifaceted role in biology and materials science. Our efforts towards unveiling these roles led to xanthine derivatives that form higher-order structures with quadruplex-forming abilities. In this paper we present further modifications of the xanthine core resulting into 9-deaza and 8-aza-9-deaza heterocycles (pyrrolo[3,2-d]pyrimidines and pyrazolo[4,3-d]pyrimidines) that form tetrads and other higher-order structures. Additionally, the ring contraction of 2',3'-O-isopropylideneuridine gave rise to the formation of an imidazolidine-4-carboxylic acid nucleoside derivative. Our computational predictions forecasted that the latter derivative will form stable triads.

Hydrazine derivatives are known as an organic compounds group containing C=N-N=C functional groups. This π-conjugated system enables electronic excitation in the visible and near ultraviolet regions. This is of particular interest for many applications, such as corrosion inhibition dye-sensitized solar cells (DSSC), organogels and fluorescent probes for analytical testing. In addition, many hydrazine derivatives show notable biological and therapeutic activities such as treatment of tuberculosis, Parkinson's disease and hypertension. Schiff bases form an outstanding class of ligands because of their unique properties, such as stability under different conditions, diversity of donor sites, flexibility of synthesis, and formation of ranges in various coordination geometries of a wide range of complexes. Their complexes have received widespread attention due to their wide range of applications, such as catalysis, electrochemistry, biological sciences, optics, guest chemistry and molecular recognition. Therefore, from a theoretical and practical point of view, the synthesis of hydrazine derivatives is an important issue. In the present work, we have described a new, efficient and environment benign synthetic method for the formation of hydrazine derivatives via heterogeneous catalysis starting from ketones.

Purpurogallin (1,7,8,9-tetrahydroxy-2H-benzo[7]annulen-2-one) is a benzotropolone displaying a dienic system and known to inhibit TLR1/TLR2 activation pathway system. We have recently described the easy green synthesis of purpurogallin from pyrogallol catalyzed by a copper complex or by vegetable oxidases. Moreover, Purpurogallin was acetylated and the tetraacetate obtained can be converted with various dienophiles (benzoquinone, maleic anhydride, ethylmaleimide, azodicarboxylate…) in Diels-Alder products. The results obtained will be presented and discussed. Theoretical calculations using the conceptual DFT have been performed.

Tertiary phosphines, 1H-phosphines and 1H-phosphine oxides are widely used in organoelement and organometallic synthesis, hydrophosphinylation of alkenes and alkynes, as well as ligands and analogs of known biologically active compounds. Cyclic 1H-phosphine oxides are of practical interest as key monomers for the preparation of new reagents in organic synthesis and ligands of catalytic systems. However, in the literature there are a limited number of examples of the synthesis of cyclic 1H-phosphine oxides.
We have recently developed a one-pot method for the synthesis of alkyl(aryl)phospholanes and phospholenes in high yields, based on the in situ substitution reaction for aluminum atoms in aluminacyclopentanes by phosphorus atoms using alkyl(aryl)phosphorodichlorides. In the development of ongoing research on the development of effective methods for the synthesis of cyclic organophosphorus compounds, we have developed an effective one-pot method for the synthesis of new 3R-substituted and norbornane-annelated 1H-phospholanoxides by the reaction of substituted aluminacyclopentanes with phosphorus trihalide. Substituted aluminacyclopentanes were prepared in situ by the reaction of cycloaluminization of α-olefins and norbornene derivatives with triethylaluminum in the presence of bis(cyclopentadienyl)zirconium(IV) dichloride catalyst.
Thus, we have proposed an original one-pot method for the synthesis of 3R-substituted and norbornane-annelated 1H-phospholanoxides, which are of practical interest as precursors for obtaining catalysts for homogeneous catalysis.

In the present work, the synthesis and biological activities of substituted 2-aminopyridine δ-lactone derivatives were achieved. 4,6,6-trimethyl-2-oxo-5,6-dihydro-2H-pyran-3-carbonitrile was synthesised from 4-hydroxy-4-methylpentan-2-one, followed by its transformation in enaminonitrile with DMFDMA. Then, the latter can react with various amines giving substituted 2-aminopyridine δ-lactones characterised by spectroscopic methods (IR, ¹H NMR, ¹³C NMR and MS). The antioxidant effects of substituted 2-aminopyridine δ-lactone derivatives were evaluated through DPPH assay and revealed a great antioxidant capacity. The antifungal and antibacterial activities were investigated by disc diffusion method against clinical Gram-negative bacteria and against clinical fungi. The study shows moderate to very good antibacterial and antifungal activities for the new substituted 2-aminopyridine δ-lactone derivatives.

Various copper complexes were prepared (CuCl(phen), CuCl(bipy), CuCl(neocu), CuCl(BPA), [CuCl(OH)(tmeda)]₂) and tested in aerobic room temperature oxidation of p-cresol. The complexe [CuCl(OH)(tmeda)]₂ was found to be the more efficient and was used in o,o and p,p coupling of various phenols and in the formation of quinones under aerobic conditions. The dimerisation of substituted naphthols was also studied.

This C-H activation with formation of one C-C bond and one harmless molecule of water with air as oxidant at room temperature represents a biomimetic model of enzyme Laccase.

Hydrazone-type Schiff bases derived from natural compounds had demonstrate to be effective and versatile antioxidants. Particularly, the interest of this work is to analyze the antioxidant activity of cinnamaldehyde phenylhydrazone (CPH), an effective antioxidant synthesized by our group, through theoretical calculations. Considering that the enzymes cytochrome P450 (CP450) and NADPH oxidase (NO) are associated with the oxidative stress process, we chose these enzymes to evaluate their interaction with the antioxidant CPH. The interactions were analyzed by coupling studies performed with the SwissDock server. Considering the parameters of the scoring function based on the energy of the system, the best protein-ligand binding geometries were obtained and the interaction distances between the CPH enzymes were studied. Taking into account the information from all the data obtained, it could be concluded that CPH has strong interactions with enzymatic substrates due to electrostatic interactions with amino acid residues present in segments corresponding to hydrophobic domains. These results attest to the significant antioxidant capacity of CPH observed in experimental antioxidant tests.

Dyes and pigments have many applications, and their growing development is driven by their increased use. As a contribution to this topic, in this work, the synthesis of functionalized pararosaline was evaluated with the aim to obtain an amphiphilic dye. Pararosaline is a dye highly soluble in water and polar solvents, presenting three amino groups in its structure. We realized that the functionalization of pararosaline by direct coupling of amino groups with halogenated fatty acids leads to amides derived from fatty acid. In the synthesis, fatty acid chloride from sunflower oil and basic catalysts were used. Over a single step one-pot procedure carried out at room temperature in moderate reaction time, a new functionalized pararosaline was synthesized. The results showed that after derivatization with chloride of fatty acids, the dye exhibits solubility both in water and in non-polar systems with different color intensities.

Coccoloba cowellii Britton (Polygonaceae, order Caryophylalles) is an endemic and critically endangered plant species that only grows in the municipality of Camagüey, province of Cuba. Pre-liminary investigation of its total methanolic extract led to the discovery of a promising antifungal activity. The major constituents of the aforementioned extract were glucuronides and glycosides of myricetin and quercetin, proanthocyanidins (tentatively characterized by means of HRMS), as well as epichatechin-3-O-gallate, catechin, epicatechin and gallic acid (tentatively characterized by using HRMS and authentic standards). A UHPLC-ESI-QTOF-MS analysis of the methanol 90% fraction (MeOH90-F) derived from the total extract, allowed the identification of flavonoid glycosides/glucuronides, lignin oligomers, and methoxyflavonoids as the main constituents of that fraction. A combination of flash chromatography, 1D and 2D NMR, and NMR-based machine learning tool “Small Molecule Accurate Recognition Technology” (SMART 2.1, available at https://smart.ucsd.edu/classic) allowed the isolation from MeOH90-F of quercetin and four methoxyflavonoids: 3-O-methylquercetin, myricetin 3,3',4'-trimethyl ether, 6-methoxymyricetin 3,4'-dimethyl ether and 6-methoxymyricetin 3,3',4'-trimethyl ether. This report contributes to a better understanding of the phytochemistry of the genus Coccoloba.

Pyrazoles and their derivatives have attracted particular attention because they have a wide variety of biological activities, and recently, we found that 4,4´-(arylmethylene)-bis-(1-phenyl-3-methyl-1H-pyrazole-5-ols) have good leishmanicidal activity against promastigotes of Leishmania mexicana. 4-Arylidenepyrazolones derivatives also have antiparasitic activity and are the intermediated in the synthesis of these bispirazoles that are formed by the equimolar reaction of 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one with aromatic aldehydes. In order to obtain new compounds with potential leishmanicidal activity, we want to synthesize several 4-arylallylidenepyrazolones derivatives through the reaction of pyrazol-3-one with different cinnamaldehydes. We report here the synthesis of some 4-arylallylidene derivatives from the reaction between 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one and substituted cinnamaldehydes. Using the reaction of 4-nitrocinnamaldehyde as a model, we found that L-proline and FeCl₃ are the best catalysts, and also we observed a solvent effect in the reaction. Our preliminary results indicate that aprotic solvents favor the formation of the 2Z isomer instead the 2E isomer.