Friedel-Craft acylation at 100 °C of 2,5,9,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene [ar-himachalene (1)], a sesquiterpenic hydrocarbon obtained by catalytic dehydrogenation of α-, β- and γ-himachalenes, produces a mixture of two compounds: (3,5,5,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yl)-ethanone (2, in 69% yield), with a conserved reactant backbone, and 3, with a different skeleton, in 21% yield. The crystal structure of 3 reveals it to be 1-(8-ethyl-8-hydroperoxy-3,5,5-trimethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-ethanone. In this compound O-H…O bonds form dimers. These hydrogen-bonds, in conjunction with weaker C-H…O interactions, form a more extended supramolecular arrangement in the crystal.

Using ZnAl2O4@ZnO as a catalyst, an environmentally friendly and very effective method has been developed to selectively add a ring to 1,3-dicarbonyl compounds and aromatic, aliphatic primary amines. A wide variety of bis(β-enaminones) and bis(β-enaminoesters) can be synthesized using this highly versatile method, which provides good yields. This procedure can be carried out at room temperature, which is environmentally advantageous as it utilizes ZnAl2O4@ZnO as a heterogeneous, recyclable and stable catalyst under free solvent conditions. A co-precipitation reaction at constant pH was used to prepare this catalyst, and spectral analysis (X-ray diffraction, FTIR) and morphological characterization techniques (SEM, EDX) confirmed its morphological structure.

Herein, nine square planar trans-arylbis(triphenylphosphine)palladium halides (PdX(PPh₃)₂Ar) were synthesized and fully characterized. The molecular structure of two complexes (1 and 2) have been determined by both X-ray diffraction and described thanks to Hirshfeld surface analysis. Investigation of the antioxidant activities showed that most of the complexes exhibit a strong dose-dependent radical scavenging activity towards DPPH radical as well as in the ABTS radical scavenging test. Complexes 1 [PdI(PPh₃)₂(4-MeOC₆H₄)] and 3 [PdCl(PPh₃)₂(4-MeOC₆H₄)] showed the highest activity in the DPPH assay with EC₅₀ values of 1.14 ± 0.90 and 1.9 ± 0.87 µM, respectively. In contrast, for the ABTS assay, quercetin (5.56 ± 0.97 µM) was slightly more efficient than the three complexes 1 (5.78 ± 0.98 µM), 2 (7.01 ± 0.98 µM), and 3 (11.12 ± 0.94 µM). The use of kinetic studies as a powerful parameter shows that complexes 1, 2, and 3 displayed the best antioxidant efficiency. The antioxidant effect of the nine palladium complexes has been also evaluated on the enzyme-catalyzed oxidation of the L012 probe (using HRP/H₂O₂) by using a chemiluminescence technique. As with the last model, complexes 1, 2, and 3 showed the best activity, with EC50 values of 3.56 ± 1.87, 148 0.71, and 5.8 ± 2.60 µM, respectively. Interestingly, those complexes (1, 2, and 3) even exhibited a higher dose-dependent activity than the quercetin (7.06 ± 2.56 µM) used as a standard. Taken together, the combined results reveal that the antiradical and enzyme (HRP) inhibitory activity of complexes decrease following the ligand order of p-OMePh > p-OAcPh >> Ph.

The title compound 3-(2,4,6-timethyl-phenylamino)-but-2-enoate was obtained by condensation reaction of ethyl acetoacetate and 2,4,6-trimethyl-phenylamine. X-ray structural analysis identified the structure of the synthetized β-enaminoester, NMR spectroscopy complemented it, and the structure stabilized by intramolecular interactions. The intermolecular contacts were further analysed by the mapping of contacts descriptors dnorm, de, di, the shape-by-Shape index and surface property by electrostatic potential mapped on the Hirshfeld surface (HS). Data from density functional theory (DFT) was compared to experimental results for this process. Global reactivity factors such electronegativity, chemical hardness, potential, and softness were calculated using DFT. The effects of the molecular environment were accessed by analysing the electrostatic potentials surface mapped over the HS and the 3D-topology of energy frameworks. As a potential bioactive molecule, the physicochemical and ADME-Tox predictions were performed suggesting that compound 3 could be considered as promising drug candidate.