Youssef Ramli

Pharmacological Profile of Quinoxalinone

Quinoxalinone and its derivatives are used in organic synthesis for building natural and designed synthetic compounds and they have been frequently utilized as suitable skeletons for the design of biologically active compound. This review covers updated information on the most active quinoxalinone derivatives that have been reported to show considerable pharmacological actions such as antimicrobial, anti-inflammatory, antidiabetic, antiviral, antitumor, and antitubercular activity. It can act as an important tool for chemists to develop newer quinoxalinone derivatives that may prove to be better agents in terms of efficacy and safety.

Crystal structure of 1-ethyl-pyrazolo[3,4-d]pyrimidine-4(5H)-thione.

In the title compound, C7H8N4S, the methyl C atom is displaced by 1.232 (7) Å from the mean plane of the pyrazolo[3,4-d]pyrimidine ring system (r.m.s. deviation = 0.007 Å). The N—N—C—Cm (m = methyl) torsion angle is −60.3 (6)°. In the crystal, molecules are linked by N—H⋯S hydrogen bonds, generating [010] chains, which are reinforced by C—H⋯N interactions. The chains are cross-linked by weak C—H⋯S hydrogen bonds, generating (001) sheets.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Crystal structure of 4-allyl­sulfanyl-1H-pyrazolo­[3,4-d]pyrimidine

In the title compound, C8H8N4S, the pyrazolo[3,4-d]pyrimidine ring system is essentially planar, with a maximum deviation from the mean plane of 0.025 (3) Å. The allyl group is disordered over two sites in a 0.512 (6):0.488 (6) ratio. In the crystal, molecules are linked by pairs of N—H⋯N hydrogen bonds, forming inversion dimers with an R 2 2(8) graph-set motif.

N′-Phenyl-N′-[3-(2,4,5-triphenyl-2,5-di­hydro-1H-pyrazol-3-yl)quinoxalin-2-yl]benzohydrazide

The molecule of the title compound, C42H32N6O, is built up from one pyrazole ring linked to three phenyl rings and to an approximately planar [maximum deviation = 0.0455 (15) Å] quinoxaline system connected to a phenylbenzohydrazide group. The pyrazole ring assumes an envelope conformation, the C atom attached to the quinoxalin-3-yl ring system being the flap atom. The dihedral angle between the two phenyl rings of the phenylbenzohydrazide group is of 58.27 (9)°. The mean plane through the pyrazole ring is nearly perpendicular to the quinoxaline ring system and to the phenyl ring attached to the opposite side, forming dihedral angles of 82.58 (7) and 87.29 (9)°, respectively. An intramolecular C—H⋯O hydrogen bond is present. In the crystal, molecules are linked by pairs of N—H⋯N hydrogen bonds, forming inversion dimers, which are further connected by C—H⋯N hydrogen bonds into chains parallel to the b axis.

5-(Pyridin-4-ylmeth-yl)-1H-pyrazolo-[3,4-d]pyrimidin-4(5H)-one.

In the title compound, C11H9N5O, the pyrazolopyrimidin-4-one ring system is almost planar, with a maximum deviation of 0.0546 (13) Å for the O atom. The crystal packing is stabilized by intermolecular N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds. In addition, π–π stacking is found between the pyridine ring and the pyrazolopyrimidin-4-one ring systems, with centroid–centroid distances in the range 3.9627 (12)–4.6781 (12) Å.

N′-(3-Methyl­quinoxalin-2-yl)-N′-phenyl­benzohydrazide

In the crystal structure of the title compound, C22H18N4O, the quinoxaline system makes dihedral angles of 86.59 (7) and 63.37 (9)° with the benzohydrazide and phenyl rings, respectively. The benzohydrazide ring makes a dihedral angle of 72.46 (10)° with the phenyl ring. The crystal structure is stabilized by intermolecular N—H⋯O hydrogen bonds, C—H⋯O contacts and C—H⋯π interactions.

New Pyrazole-Hydrazone Derivatives: X-ray Analysis, Molecular Structure Investigation via Density Functional Theory (DFT) and Their High In-Situ Catecholase Activity

The development of low-cost catalytic systems that mimic the activity of tyrosinase enzymes (Catechol oxidase) is of great promise for future biochemistry technologic demands. Herein, we report the synthesis of new biomolecules systems based on hydrazone derivatives containing a pyrazole moiety (L1–L6) with superior catecholase activity. Crystal structures of L1 and L2 biomolecules were determined by X-ray single crystal diffraction (XRD). Optimized geometrical parameters were calculated by density functional theory (DFT) at B3LYP/6–31G (d, p) level and were found to be in good agreement with single crystal XRD data. Copper (II) complexes of the compounds (L1–L6), generated in-situ, were investigated for their catalytic activities towards the oxidation reaction of catechol to ortho-quinone with the atmospheric dioxygen, in an attempt to model the activity of the copper containing enzyme tyrosinase. The studies showed that the activities depend on four parameters: the nature of the ligand, the nature of counter anion, the nature of solvent and the concentration of ligand. The Cu(II)-ligands, given here, present the highest catalytic activity (72.920 μmol·L−1·min−1) among the catalysts recently reported in the existing literature.

The crystal structure of 1,5-dibenzyl-1H-pyrazolo-[3,4-d]pyrimidine-4(5H)-thione.

In the title compound, C19H16N4S, the pyrazolo[3,4-d]pyrimidine ring is close to being planar, with the greatest deviation from the mean plane being 0.023 (2) Å for the C atom bearing the thione S atom. The two phenyl rings are nearly perpendicular to the fused ring system [dihedral angles = 71.4 (2) and 78.1 (2)°], but are oriented in opposite directions; the dihedral angle between the phenyl rings is 32.22 (16)°. In the crystal, linear supramolecular chains along [101] are sustained by C—H⋯S interactions.

Crystal structure of 1-methyl-4-methyl­sulfanyl-1H-pyrazolo­[3,4-d]pyrimidine

In the title compound, C7H8N4S, the non-H atoms of the pyrazolo[3,4-d]pyrimidine ring system and the methylsulfanyl group lie on a crystallographic mirror plane. In the crystal, molecules are linked via a number of π–π interactions [centroid–centroid distances vary from 3.452 (7) to 3.6062 (8) Å], forming a three-dimensional structure.